Provided by: taktuk_3.7.6-1_all 
NAME
TakTuk - a tool for large scale remote execution deployment
SYNOPSIS
taktuk [-behinsvzMP] [-c connector] [-d limit] [-f filename] [-g duration] [-l login] [-m hostname [-[
args ... -]]] [-o stream=template] [-t timeout] [-u limit] [-w size] [-B parameter=expression] [-C
separators] [-E character] [-F filename] [-G hostname [-[ args ... -]]] [-L hostname] [-I interpreter]
[-O separators] [-R stream=filename] [-S files] [-T command] [-V path ] [-W scheme] [commands ... ]
DESCRIPTION
TakTuk is a tool for broadcasting the remote execution of one ore more commands to a set of one or more
distant machines. TakTuk combines local parallelization (using concurrent deployment processes) and work
distribution (using an adaptive work-stealing algorithm) to achieve both scalability and efficiency.
TakTuk is especially suited to interactive tasks involving several distant machines and parallel remote
executions. This is the case of clusters administration and parallel program debugging.
TakTuk also provides a basic communication layer to programs it executes. This communication layer uses
the communication infrastructure set up by TakTuk during its deployment. It is available both for the
Perl and the C langages and is described in TakTuk(3) and taktukcomm(3) respectively.
OPTIONS
Caution, in TakTuk options are parsed in the order given on the command line. This means that TakTuk is
not POSIX compliant regarding options order. This is important as some of the options change the
behavior of following ones (and only these ones - e.g. -l applies to following -m options). The defaults
settings of TakTuk can be obtained by using the "--print-defaults" option. The following options are
given by category in alphabetical order.
DEPLOYMENT OPTIONS
-b
--begin-group
begins a new deployment group. A deployment group acts both as a context for most options (options
set within a group have no effect outside the group) and as an isolation for deployment tasks
scheduling (deployment tasks within a group cannot be stolen by nodes deployed in other groups).
-c connector
--connector connector
defines the connector command used to contact the following remote machines.
-d limit
--dynamic limit
turns dynamic mode (work stealing) on or off for the deployment of all the following remote machines
specifications. If "limit" is positive or null, TakTuk uses the dynamic mode with its value as a
maximal arity (0 = no maximal arity). A negative value for "limit" turns dynamic mode off. Warning,
currently it is a bad idea to use several -d options with positive values on the same command line.
-e
--end-group
ends a deployment group.
-f filename
--machines-file filename
"filename" is the name of a file that contains remote machines names (equivalent to several "-m"
opions). In each line of this file, the first word is considered as a machine name and the remaining
as comments.
-l login
--login login
sets the login name for the following hosts. This assumes that the connector command accepts "-l"
option (this is the case for ssh, the default).
-m hostname
--machine hostname
"hostname" is the name of a remote machine on which TakTuk has to be deployed. "hostname" might
contain list of values specified inside brackets and exclusion lists (see "HOSTNAMES SPECIFICATION").
In such case, the depolyment will be performed on all the matching hosts. This option can be
followed by any number of arguments enclosed between "-[" and "-]" which will be transmitted as
arguments of the remote TakTuk that will execute on all the target hosts.
-s
--self-propagate
propagates the TakTuk executable through the following connectors and thus eliminates the need for a
TakTuk installation on remote machines.
-z
--dont-self-propagate
cancels a preceding -s option.
-F filename
--args-file filename
"filename" is the name of a file that contains additional options for TakTuk. The parsing of the file
is done when encountering this option.
-G hostname
--gateway hostname
same as -m hostname, except that the deployed node(s) are considered as forward-only nodes: they will
not be numbered and will not be targeted by subsequent diffusion commands. As an exception, execution
of TakTuk commands on those nodes is still possible by giving them as deployment arguments of the -G
option.
-I command
--perl-interpreter command
"command" is the name of the command to use as a Perl interpreter when auto propagating or when using
the "taktuk_perl" command.
-L hostname
--localhost hostname
changes the name of localhost as viewed by TakTuk.
-S files
--send-files files
gives to TakTuk a list of files to be sent upon successfull remote connection. Use with caution as it
will slow down deployment (the files are transfered before the end of the deployment). The intended
use is NOT to transfer application data files (rather use the "put" command to transfer such files).
This option should be used to transfer files that are necessary to perform further connections from
the remote node. "files" is a comma separated list of pairs "local_file:remote_file". Regarding the
transfer itself, it behaves as the "put" command.
-T command
--taktuk-command command
"command" is the name of the TakTuk command (default is $0, the name used to launch TakTuk). This is
the command used once connected to initiate the remote TakTuk engine. Note that the effect of this
switch is void when using the "-s" option.
-V list
--path-value list
set the PATH environment variable to the given list (as usual, a colon separated directories list) on
remote hosts to which TakTuk connects. This is performed very early and is taken into account even
for "taktuk" or "perl" invocations at connection time.
COMMAND LINE PARSING OPTIONS
-C separators set
--command-separator separators set
replaces the default set of characters that separates successive TakTuk commands.
-E character
--escape-character character
defines an escape character that can be used to protect any following character from TakTuk
interpretation. This protection applies nearly to the whole TakTuk command line.
-O separators set
--option-separator separators set
replaces the default set of characters that separates successive words when reading options and
commands from a file (using the "-F" switch).
I/O OPTIONS
-o stream=template
--output-template stream=template
sets an output template specification for one of output streams designed by the given name. When
giving only a stream name (without template) this disables the stream. Available streams include :
"connector" (errors from the connector command)
this stream contains in $line information outputed to stderr by a connector command. Relevant
fields include $host, $peer and others listed below.
"error", "output" (error and output of remotely executed commands)
these streams contain in $line information outputed by executed command to stdout or stderr
(respectively). Relevant fields include $host, $command, $pid and others listed below.
"info" (general information such as help summary or version)
this stream contains in $line information outputed by taktuk in response to commands such as
"help" or "version".
"message" (messages from running processes)
each output of this stream contains in $line a message sent with target "output" (through TakTuk
out-of-band communications facilities) by some processus started using TakTuk commands. Relevant
fields for this stream include $from and $to and others listed below.
"state" (internal state of TakTuk instance)
this stream contains in $line the state change code matching some TakTuk events. Codes are the
following:
0 - TakTuk is ready
1 - TakTuk is numbered
2 - TakTuk terminated
3 - connection failed
4 - connection initialized
5 - connection lost
6 - command started
7 - command failed
8 - command terminated
9 - numbering update failed
10 - pipe input started
11 - pipe input failed
12 - pipe input terminated
13 - file reception started
14 - file reception failed
15 - file reception terminated
16 - file send failed
17 - Invalid target
18 - No target
19 - Message delivered
20 - Invalid destination
21 - Destination not available anymore
22 - Wait complete
23 - Wait reduce complete
The function event_msg($) can be used in the template to translate this code into a string that
describes the event. Relevant fields include $host, $position, $rank, $count and others listed
below.
"status" (commands exit status)
this stream contains in $line the return code of executed commands. Relevant fields include
$host, $pid and others listed below.
"taktuk" (internal messages, warnings and errors)
this stream contains in $line error, warning and debug messages outputed by TakTuk itself.
Relevant fields include $line_number, $package and others listed below.
a template is a Perl expression that should evaluate to the string eventually displayed. Within a
specification, some variables might be used depending on the concerned stream:
$command (not for "taktuk" nor "info")
the command line execution that generated output.
$count
the total number of TakTuk instances.
$eol
an empty string or a newline depending on what character ended command output.
$filename ("taktuk" only)
the file in which a TakTuk diagnostic function has been called.
$from ("message" only)
the logical number of the TakTuk instance from which the message has been sent.
$host
the name of the host executing the current TakTuk instance
$init_date ("connector" and "state" only)
the time in seconds since Jan. 1, 1970 at which the remote TakTuk instance completed its
initialization (including ssh connection time and self propagation if any).
$level ("taktuk" only)
the level of the diagnostic function called.
$level_name ("taktuk" only)
the name associated with the level of the diagnostic function called.
$line
the raw data outputed by a command or passed to a diagnostic function, any trailing newline
removed (see $eol).
$line_number ("taktuk" only)
the line number at which a TakTuk diagnostic function has been called.
$package ("taktuk" only)
the package in which a TakTuk diagnostic function has been called.
$peer ("connector" and "state" only)
the remote machine for which a connector command outputed information.
$peer_position ("connector" and "state" only)
position on the command line of the remote host. This position is expressed as a path in the
hierarchy of hosts expressed on the command line (dot separated position number at each level of
imbrication).
$peers_given ("state" only)
a space separated list of remote nodes that has been given to the remote peer for deployment
(whatever their deployment state). Each remote node is specified as a colon separated couple made
of its hostname and its position on the command line. This variable has only a meaningful value
when the event outputed to the stream "state" is a connection loss (event number 5).
$pid (not for "taktuk" nor "info")
the pid of the command line executed (that produced output).
$position
position on the command line of the current host. This position is expressed as a path in the
hierarchy of hosts expressed on the command line (dot separated position number at each level of
imbrication).
$rank
the logical number of TakTuk instance in which output is collected.
$reply_date ("connector" and "state" only)
the time in seconds since Jan. 1, 1970 at which the connector command replied to the local TakTuk
instance (note that this does not include the initialization exange occuring before the remote
TakTuk is considered as functional).
$start_date ("output", "error", "connector" and "status")
the time in seconds since Jan. 1, 1970 at which the command started (taken just after the call to
fork()).
$init_date ("connector" and "state" only)
the time in seconds since Jan. 1, 1970 at which the remote TakTuk completed its initilization.
$stop_date ("connector" and "status" only)
the time in seconds since Jan. 1, 1970 at which the command terminated (after the closing of its
stdout).
$to ("message" only)
the logical number (or set of such numbers) of the TakTuk instance to which the message has been
sent.
$type
the name of the output stream (connector, error, output, ...).
$user_scalar
a scalar, global to the package, initially initialized to undef, that the user is free to use for
any purpose.
at the end of the day, the specification is evaluated for each line of the concerned stream and the
result printed on the root node. Note that the newline has to be added explicitly as "\n" in the
template if needed.
WARNING: take care of your specification, if the Perl syntax is not correct lots of awfull
compilation error messages will be displayed and TakTuk execution will fail.
-R stream=filename
--output-redirect stream=filename
redirect a given stream output to a given file (located at the root node). Notice that the given
filename comply with Perl open syntax: for instance, one might redirect to a file descriptor X using
the name ">&=X". See "-o" option for more details about streams output.
PERFORMANCE TUNING OPTIONS
-B parameter=expression
--worksteal-behavior parameter=expression
caution: this feature should be considered as experimental and could be removed from future releases.
Tunes finely the behavior of the work-stealing algorithm by setting some its parameters to Perl
expressions. These Perl expressions can use the variables $last_given and $available which are
respectively equal to the number of tasks given to a stealer last time it stole and to the total
number of remaining deployment tasks. Available parameters are :
initial
the number of tasks given to a remote TakTuk instance the first time it send a steal request to
the local host.
growth
the number of tasks given to a remote TakTuk instance each time it performs a steal to the local
host after the first time.
limit
an upper bound to the value resulting from the evaluation of "growth".
-g duration
--time-granularity duration
sets to "duration" (in seconds) the maximal interval between timeouts checks (usually checks are made
more often: at each message received a timeouts check is made).
-n
--no-numbering
disables TakTuk logical numbering and the variables "TAKTUK_COUNT" and "TAKTUK_RANK" are not defined
in executed commands. This has the advantage of removing the global synchronization occuring at the
end of the deployment and making the deployment more efficient.
WARNING: use this option only before any remote node specification ("-m" or "-f") otherwise you might
get serious synchronization issues in TakTuk. Using TakTuk point-to-point communication along with
this option will fail and produce TakTuk warnings.
-t timeout
--timeout timeout
sets the timeout (in seconds) for following connectors (0 = no timeout). Notice that this option
override the timeout of the connector command ("ssh" for instance). When the delay expires, the
connector command is simply killed.
-u limit
--cache-limit limit
limits a number of memory bytes TakTuk might use as an internal write buffer. For most users, setting
such a limit is a bad idea : in some rare situations it might result in a deadlock in TakTuk (caused
by parallel blocking writes between an application and TakTuk itself). Setting this option to a
negative value disables the limit (default).
Nevertheless, if you use TakTuk to transfer large files, because of I/O bandwith disparities in
various parts of a system, TakTuk memory use might grow too large and performance can be severely
degraded when the system starts swapping. In such situations, limiting the size of the internal cache
will keep TakTuk in main memory and preserve the performance.
-w size
--window size
sets initial window to the given size (= pipeline width).
-W scheme
--window-adaptation scheme
sets the windows adaptation scheme to number (default is 0, 0: no adaptation, 1: implementation in
progress).
MISCELLANEOUS OPTIONS
-M
--my
makes the next option local (not inherited). This means that the next option is set only for the
local host and not propagated to children TakTuk instances. Has no effect if the next option is
already a local one.
-h
--help
prints a short description of TakTuk on the screen.
-i
--interactive
forces TakTuk interactive mode even after some batch commands given on the command line.
-v
--version
prints the TakTuk version.
-P
--print-defaults
prints the defaults settings used by TakTuk (environment variables taken into account).
INTERNAL OPTIONS
These option are not useful for most users. They are used either internally by TakTuk itself or for
development purposes.
-p packagename
--print-package packagename
prints the content of package "packagename" extracted from the taktuk code in execution.
-r
--not-root
current TakTuk instance is not the root node. This is an internal switch used by spawned TakTuk
instances. This is usually not useful for most users.
-D scope=level
--debug scope=level
sets debugging level (1..4) for "scope". The "scope" might be a TakTuk package name or "default" and
the lowest the level the more verbose the output.
COMMANDS
After the options parsing, TakTuk expects some commands either on the remaining of the command line
(batch mode) or on the standard input (interactive mode). These commands are actions to be performed by
TakTuk using the logical network infrastructure set up during the deployment. By default, commands might
be separated by ; or newlines. For all the commands, any non ambiguous prefix can be used instead of
their full name. In interactive mode, TakTuk has support for "readline" (history, command line editing)
if installed on your system.
When TakTuk commands accept arguments, they should be enclosed into matching delimiters (indicated by *
below). In other words, * might be replaced either by any non alphanumeric character or by a pair of
matching braces, brackets or parenthesis. These delimiters must be separated from their content (using
the options separator). If the argument contains a closing delimiter preceded by a separator, then it is
probably a good idea to escape it (see -E option) or to protect the whole arguments string if given on
the command line.
Taktuk understands the following commands:
[ set specification ] command
Sends the execution of command to all the peers belonging to the given set. For more details about
the set specification, see section "SET AND TARGETS SPECIFICATION".
broadcast command
Broadcasts the execution of command on all the remote peers (not including the node initiating the
broadcast).
downcast command
Spreads the execution of command on all the children of the node initiating the downcast (not
including itself).
exec parameters * command line *
Executes the "command line" on the local machine. Inputs/outputs of the execution are multiplexed
and fowarded to the TakTuk root. This command accepts optional parameters that enable the attachment
of callbacks triggered by timeouts to the execution of the command. See section "EXEC PARAMETERS" for
more details.
get * src * * dest *
Copies (a) remote source(s) (present on the remote node(s)) to a destination on the node executing
this command. The type of source and destination is quite similar to those accepted by the "cp -r"
command (that is file or directories). This command also performs some kind of magic with its
parameters: shell environment variables present in the source or destination names are replaced by
their respective value on the remote and local nodes. In addition, the variables $host, $rank and
$position of the remote node (which are the same as in -o option) can also be used in both names.
help
Prints a very concise TakTuk help.
input [ target target ] * data *
input [ target target ] data * data *
Sends the given data as input to commands in execution on the local machine as specified by the given
target. If no target is given, the data is sent to all commands. For more details about targets, see
"SET AND TARGETS SPECIFICATION"
input [ target target ] close
Closes the inputs descriptor of executing commands on the local machine as specified by the given
target. If no target is given, the inputs of all commands are closed.
input [ target target ] file * filename *
Sends the content of a file (which must be local to the node executing the input file) as input to
commands in execution on the local machine as specified by the given target. If no target is given,
the data is sent to all commands.
WARNING: this command is not atomic. If you manage somehow to initiate a input file command from two
different TakTuk instances, data will probably be interleaved. In this case you should synchronize
the two instances. This is not required when spreading files only from the root node.
input [ target target ] line * data *
Sends the given data with an additional newline as input to commands in execution on the local
machine as specified by the given target. If no target is given, the data is sent to all commands.
input [ target target ] pipe * filename *
Treat the parameter as a file (which must be local to the node executing the input pipe) which
behavior is the same as a pipe: data can arrive continuously. TakTuk add it as one of its input
channels and send data as input to commands when available. If given, the target specifies to which
command the data are to be sent, otherwise it is sent to all commands.
kill [ target target ] <signal>
Sends the given signal to local commands processes groups. If no signal is given, sends a TERM signal
(signal 15). If given, the target specifies to which command the signal is to be sent, otherwise it
is sent to all commands. For more details about targets, see "SET AND TARGETS SPECIFICATION"
message [ target target ] * data *
message [ target target ] data * data *
Sends the given data as a message to commands in execution on the local machine as specified by the
given target (see TakTuk(3) and taktukcomm(3) for more details about messages). If no target is
given, the data is sent to the first command peforming a receive and not already targeted by another
message. For more details about targets, see "SET AND TARGETS SPECIFICATION"
message [ target target ] file * filename *
Sends the content of a file (which must be local to the node executing the message file) as a message
to commands in execution on the local machine as specified by the given target (see TakTuk(3) and
taktukcomm(3) for more details about messages). If no target is given, the data is sent to the first
command peforming a receive and not already targeted by another message.
WARNING: this command is not atomic. If you manage somehow to initiate a message file command from
two different TakTuk instances, data will probably be interleaved. In this case you should
synchronize the two instances. This is not required when spreading files only from the root node.
message [ target target ] line * data *
Sends the given data with an additional newline as a message to commands in execution on the local
machine as specified by the given target (see TakTuk(3) and taktukcomm(3) for more details about
messages). If no target is given, the data is sent to the first command peforming a receive and not
already targeted by another message.
message [ target target ] pipe * data *
Treat the parameter as a filename (which must be local to the node executing the input pipe) which
behavior is the same as a pipe: data can arrive continuously. TakTuk add it as one of its input
channels and send data as a message to commands when available (see TakTuk(3) and taktukcomm(3) for
more details about messages). If given, the target specifies to which command the data are to be
sent, otherwise it is sent to the first command peforming a receive and not already targeted by
another message.
network
network state
Prints the current TakTuk deployment tree. Numbers in parenthesis match the peer rank in the logical
TakTuk numbering and the peer ready state. If the deployment is not complete, the printed tree will
display "connecting ..." leaves.
network cancel
Cancels all ongoing connections. Consequently, this causes immediate starting of the possible
numbering of TakTuk instances and the execution of TakTuk commands.
network renumber
Completely recomputes the logical numbering of TakTuk instances. This is especially useful when
adding new nodes to the deployed network after initial numbering.
network update
Updates the logical numbering of TakTuk instances without changing already existing numbers. Does not
always succeed as TakTuk uses a depth first scheme for numbering. Sends an event 9 in the stream
'state' for each node of the tree that cannot be updated while keeping TakTuk numbering scheme. This
is especially useful when adding new nodes to the deployed network after initial numbering.
option name * value *
option * line *
Either changes a single option which name is given (first form) or parses an additional options line
(second form) on the node(s) executing this command. See TakTuk options for more details, name can
be either short or long in the first form.
WARNING: new nodes added to TakTuk network using this command are not numbered. Further use of
network renumbering or update is necessary to get TakTuk logical numbering.
put * src * * dest *
Copies a local source (present on the node executing this command) to a destination on all the remote
nodes given as prefix of the command. The type of source and destination is quite similar to those
accepted by the "cp -r" command (that is file or directories). This command also performs some kind
of magic with its parameters: shell environment variables present in the source or destination names
are replaced by their respective value on the local and remote nodes. In addition, the variables
$host, $rank and $position of the local node (which are the same as in -o option) can also be used in
both names.
synchronize command
Forces the given command to wait for the completion of deployment, nodes numbering and previous
commands before executing. This is useful for global commands like "broadcast" which does not wait
for nodes numbering. In contrary, multicast commands (those that use a set specification as a prefix)
wait for the nodes numbering and the completion of previous commands. If in doubt, always use
"synchronize" before a "broadcast", "downcast" or "wait reduce".
taktuk_perl * arguments *
Forks a perl interpreter on the local node just as if the command "exec perl arguments" has been
used. The difference is that this interpreter is previously fetched with the "taktuk" package that
contains point-to-point communication routines ("TakTuk::send" and "TakTuk::recv", see
taktukcomm(3)). WARNING: due to the limitations of the parser that analyses the arguments of this
command, you have to give arguments (even if empty) and to use '--' if you give any option to the
perl interpreter (and even if you give it only options).
version
prints TakTuk version.
quit
Quit the TakTuk engine and shut down the logical communication network established during the
deployment.
wait target target
Waits (suspends the execution of following commands) in the local TakTuk instance for the completion
of some local process depending on the given target. This target might be any target specification
except "output". For more details about targets, see "SET AND TARGETS SPECIFICATION".
wait reduce target target
Can only be used in the root node. Waits (suspends the execution of following commands) for the
completion of some processes in all the deployed TakTuk instances depending on the given target. This
target might be any target specification except "output". Notice that, contrary to simple "wait"
commands, this command is synchronized the same way as "broadcast". Thus, it should be explicitly
synchronized if mixed with non broadcasted commands (otherwise it will be executed before them).
EXEC PARAMETERS
The TakTuk command "exec" accepts optional parameters. These parameters are used to specify a target id
for the command, or to attach actions triggered by timeouts to commands execution. An "exec" command
accepts any number of parameters. These parameters are interpreted from left to right using the following
syntax:
target value
Attach the (numerical) value as the target id of the executed command. This target id will be used by
any subsequent command that make use of targets (such as "input", "message", "kill" or "wait").
Caution: this value overwrite any target id that could have been automatically assigned by TakTuk.
Therefore, it is not recommended to mix the use of explicitly assigned target ids with the use of
automatically assigned target ids.
timeout value
Creates a new timeout specification. At the end of the duration expressed by the given value, it will
trigger its attached callbacks. If it has no attached callback, it will send a TERM signal to the
command. If the command execution terminates before the end of the timeout duration, the timeout is
canceled.
kill value
Attach a callback to the last defined timeout. This callback send a signal, which number is the given
value, to the timeouted command.
action command
Attach a callback to the last defined timeout. This callback executes the given TakTuk command. If it
executes some other command, it can use the environment variable "TAKTUK_PID" that contains the pid
of the timeouted command. The given TakTuk command can be any valid TakTuk command (without command
separator).
Notice that each timeout can have any number of attached callbacks. They will be processed in the order
they are given as parameters.
ENVIRONMENT
Variables that change TakTuk default behavior
Some of TakTuk defaults settings can be changed on some host using environment variables. These
settings are propagated as are other options. They are overridden by propagated settings and command
line options.
To change some default setting use the variable TAKTUK_NAME where NAME is the name of the according
long option in upper case and with dashes replaced by underscores. For option taking complex value
(such as "--debug") just add an underscore and the field you want to change in upper case at the end
of the name. Using "taktuk --print-defaults" will give you examples of names used to change default
settings. Note that defining in the environment a default setting not used by TakTuk has no effect.
You can also change some TakTuk default settings locally without propagating the change in the
deployment tree. To do this, use the variable TAKTUK_MY_NAME where name is defined as above. As
before, these local settings are overridden by propagated settings and command line options.
Variables set by TakTuk in remotely executed commands
Taktuk sets the following environment variables for all the commands it executes :
TAKTUK_CONTROL_READ, TAKTUK_CONTROL_WRITE
File descriptors, used internally by TakTuk.
TAKTUK_COUNT
The total number of successfully deployed TakTuk instances
TAKTUK_HOSTNAME
Local node hostname as given to TakTuk (on the command line)
TAKTUK_PIDS
List of pids (separated by spaces) of commands executed by the local TakTuk instance.
TAKTUK_TARGET
Target number of the currently executing process (see "SET AND TARGETS SPECIFICATION" for more
details).
TAKTUK_POSITION
Host position on the command line.
TAKTUK_RANK
The logical rank of the local instance.
TAKTUK_FATHER
The logical rank of the taktuk instance that spawned this one.
TAKTUK_CHILD_MIN
The logical rank of the lowest numbered descendent from the current taktuk instance (-1 if the
local TakTuk instance has no children).
TAKTUK_CHILD_MAX
The logical rank of the highest numbered descendent from the current taktuk instance (-1 if the
local TakTuk instance has no children).
HOSTNAMES SPECIFICATION
Hostnames given to TakTuk might be simple machine name or complex hosts lists specifications. In its
general form, an hostname is made of an host set and an optional exclusion set separated by a slash.
Each of those sets is a comma separated list of host templates. Each of these templates is made of
constant part (characters outside brackets) and optional range parts (characters inside brackets). Each
range part is a comma separated list of intervals or single values. Each interval is made of two single
values separated by a dash. This is true for all hostnames given to TakTuk (both with -m or -f options).
In other words, the following expressions are valid host specifications:
node1
node[19]
node[1-3]
node[1-3],otherhost/node2
node[1-3,5]part[a-b]/node[3-5]parta,node1partb
they respectively expand to:
node1
node19
node1 node2 node3
node1 node3 otherhost
node1parta node2parta node2partb node3partb node5partb
Notice that these list of values are not regular expressions ("node[19]" is "node19" and not "node1,
node2, ...., node9"). Intervals are implemented using the perl magical auto increment feature, thus you
can use alphanumeric values as interval bounds (see perl documentation, operator ++ for limitations of
this auto increment).
SET AND TARGETS SPECIFICATION
The TakTuk command line and the "TakTuk::send" routine accept a set specification as destination host(s).
A set specification is made of interval specifications separated by slashes. An interval specification is
either made of a single number, two numbers separated by a dash or a single number followed by a plus
symbol (this last case match the interval that goes from the number to the highest numbered TakTuk
destination). Of course the two numbers specifying an interval must be given in increasing order.
The remote peers included in a set specification are all the peer which logical number belong to at least
one interval of the set. Here are some exemples of set specifications :
1
the peer numbered 1
2-7
the peers numbered 2,3,4,5,6 and 7
2-4/1/10
the peers numbered 1,2,3,4 an 10
3+
the peers from 3 to the highest numbered
5+/1
the peers from 5 to the highest numbered and the peer 1
The target number is a number assigned by TakTuk to all processes it executes (successfully started or
not using "exec" or "taktuk_perl" commands). By default, this number starts from 0 and goes to the total
number of processes that have been executed since TakTuk launch minus one. Target processes of a
"TakTuk::send" or a TakTuk command can be expressed with the same syntax as in the case of sets.
Furthermore, TakTuk understands several special targets. The special target "all" targets all processes:
this means that the command is applied to all executing local processes (message or input data are
duplicated and sent to all of them), this is the default for the "input" and "kill" commands. The special
target "any" targets the first eligible process. In the case of a message this is the first process that
issues a "TakTuk::recv" and that is not already the target of another message, this is the default for
the "message" command. Finally, the special target "output" targets the output stream "message" rather
than a process.
EXAMPLES
The following examples illustrate the basic use of TakTuk on a few machines and the use of developer
options. Notice that TakTuk is designed to scale to much more peers than the number involved in these
examples.
Basic usage
simple deployment
the simplest way to use TakTuk is to make it selfpropagate with option "-s". In this case, the basic
remote execution of "hostname" on the host "toto.nowhere.com" can be written :
taktuk -s -m toto.nowhere.com broadcast exec [ hostname ]
In this example, "-s" asks TakTuk to propagate its own code on remote hosts. It can be removed by
installing the "taktuk" executable on "toto.nowhere.com". By the following we will assume that TakTuk
is installed on all the remote hosts.
The "-m toto.nowhere.com" describe the set of remote hosts to be contacted by TakTuk and "broadcast
exec [ hostname ]" is a command that will be executed by the TakTuk interpreter.
This example can be written in many other ways. In interactive mode, the same execution might become:
taktuk -m toto.nowhere.com
here TakTuk is blocked waiting for commands from stdin. Thus, we just have to type:
broadcast exec { hostname }
Ctrl-D
here you can notice that parameters to the "exec" TakTuk command (as all commands parameters) can be
enclosed in any reasonable pair of delimiters. We might also write the list of hosts involved in the
command in a file "machine" that contains:
toto.nowhere.com
and the TakTuk command becomes:
taktuk -f machine broadcast exec - hostname -
We could also use another file "options" that contains:
-f machine
and use it as the options line given to TakTuk:
taktuk -F options broadcast exec \( hostname \)
Finally, everything could be stored in a last file "command_line" that contains:
-f machine broadcast exec = hostname =
and the following command achieve the same result:
taktuk -F command_line
All of these variants have the same effect: they execute "hostname" on "toto.nowhere.com" and the
output of the program is forwarded to the localhost. In this case:
toto.nowhere.com: hostname: somepid: output > toto.nowhere.com
parameters braces
notice that braces for command parameters must be separated from their content. Thus, they can
contain other braces as long as no single closing brace is part of the content:
taktuk -m localhost broadcast exec [ 'if [ $RANDOM -gt 10000 ];then echo greater;else echo lower;fi' ]
In this example, quotes are necessary to prevent the shell from interpreting the "$" and ";"
characters and to prevent the closing brace for "if" toe be considered as closing the "exec" command.
In this case the variable will be interpolated only on remote hosts. This same example can also be
expressed using shortcuts and intercative mode:
taktuk -m localhost -E%
then type:
b e [ if [ $RANDOM -gt 10000 %];then echo greater;else echo lower;fi ]
Ctrl-D
Notice the closing bracket used in the test that should not be interpreted as the closing bracket for
"exec" arguments. In such case, a simpler solution is probably to use another kind of braces
taktuk -m localhost
and then:
b e { if [ $RANDOM -gt 10000 ];then echo greater;else echo lower;fi }
Ctrl-D
Usually, if you want to be safe, you can quote all commands parameters. Nevertheless, notice that
parameters should not be quoted in interactive mode as input lines are not interpreted by the shell.
exec parameters
commands executed by TakTuk can be timeouted using "exec" parameters. For instance if you want to
execute some command and send it a TERM signal after two seconds, just type:
taktuk -m localhost broadcast exec timeout 2 [ sleep 10 ]
the callback executed when a timeout occurs can also be something else than a TERM signal. This can
be another signal (KILL for instance):
taktuk -m localhost broadcast exec timeout 2 kill 9 [ sleep 10 ]
or any valid TakTuk command:
taktuk -m localhost broadcast exec timeout 2 action broadcast exec [ echo hello ] [ sleep 10 ]
or even several timeouts and several callbacks:
taktuk -m localhost b e t 2 a e [ echo hello ] k 30 t 10 k 9 [ sleep 5 ]
in this last example, the command "sleep 5" is executed by TakTuk. After 2 seconds, the first timeout
will be triggered, it will execute the command "echo hello" and send a USR1 signal to the first
command ("sleep 5"). The second timeout is set to 10 seconds. Thus, it will never occur as the "sleep
5" command will be terminated before its expiration.
topology
Usually, TakTuk deploys itself using a relatively flat tree because its default window size is quite
large (10 simultaneous ongoing connections). Using a smaller window size will result in a deeper
tree although it also depends on the local load of the deployment nodes. You can use the TakTuk
"network state" command to print the tree constructed by TakTuk.
Notice that it is usually a bad idea to use a too large window as it results in too much local load
and bad distribution of work (something like 10 is often sufficient).
You can also force TakTuk to use more specific topologies. For instance, to execute "echo $$" using a
flat-tree as deployment topology, just disable work-stealing in TakTuk:
taktuk -d -1 -m host1 -m host2 -m host3 broadcast exec [ 'echo $$' ]
and to use a chain-like topology, either encode the topology in arguments structure:
taktuk -m host1 -[ -m host2 -[ -m host3 -] -] broadcast exec [ 'echo $$' ]
or limits the arity of the dynamic tree to 1:
taktuk -d 1 -m host1 -m host2 -m host3 broadcast exec [ 'echo $$' ]
Finally, the default will use a dynamicly constructed topology:
taktuk -d 0 -m host1 -m host2 -m host3 broadcast exec [ 'echo $$' ]
lightweight grid deployment
On a lightweight grid, because of locality issues (ldap cache, network topology, ...) it seems
interesting to separate the deployment of each subcluster. To do this, it is possible to enclose the
nodes of each cluster into a separate deployment group:
taktuk -b -m node1.cluster1 -m node2.cluster1 -m node3.cluster1 -m node4.cluster1 -e -b -m node1.cluster2 -m node2.cluster2 -m node3.cluster2 -m node4.cluster2 -e broadcast exec [ hostname ]
This command has the effect of deploying TakTuk on two clusters (cluster 1 and 2) made of four nodes
(node 1 to 4), preventing deployed nodes from one cluster to be used to deploy nodes from the other
cluster. Finally, once the deployment is complete, it executes the command "hostname" on all these
nodes.
executing a distinct command on each host
each distinct host can be given its own command using arguments:
./taktuk -m host1 -[ exec [ hostname ] -] -m host2 -[ exec [ id ] -] -m host3 -[ exec [ 'echo $TAKTUK_RANK; ls' ] -] quit
but this could also be given using set specification (in this case logical number are used for
hosts):
./taktuk -m host1 -m host3 -m host8 1 exec [ hostname ], 2 exec [ id ], 3 exec [ 'echo $TAKTUK_RANK; ls' ]
or in interactive mode:
./taktuk -m host1 -m host3 -m host8
1 exec [ hostname ]
2 exec [ id ]
3 exec [ echo $TAKTUK_RANK; ls ]
Ctrl-D
Nevertheless keep in mind that in general these logical numbers do not match the position of hosts on
the command line.
script diffusion
spreading and executing a perl script named "essai.pl" on three hosts, knowing that "taktuk" and
"essai.pl" are only present on the root node is straightforward with TakTuk:
taktuk -s -m host1 -m host2 -m host3
broadcast exec [ perl -- - ]
broadcast input file [ essai.pl ]
broadcast input close
Ctrl-D
files diffusion and collection
since version 3.4, files transfer is supported directly by TakTuk. Notice that this transfer uses the
TakTuk network (usually a tree composed of ssh connections by default). This network is not efficient
for the tranfer of large files (both topologically and from a protocol point of view), so keep this
in mind when using this feature.
copying a file named "message.txt" to the "/tmp" directory of each remote host is thus as easy as:
taktuk -s -m host1 -m host2 -m host3
broadcast put [ message.txt ] [ /tmp ]
Ctrl-D
but the older method still works (and does almost the same as the previous command):
taktuk -s -m host1 -m host2 -m host3
broadcast exec [ cat - >/tmp/message.txt ]
broadcast input file [ message.txt ]
broadcast input close
Ctrl-D
although it requires to be more careful about shell interpretation when typing everything directly on
the command line:
taktuk -s -m host1 -m host2 -m host3 broadcast exec [ 'cat - >/tmp/message.txt' ]\;broadcast input file [ message.txt ]
notice in this latter command that the "input close" is not necessary as TakTuk closes inputs of all
spawned commands when quitting.
the "get" command also makes possible things that were previously very difficult in TakTuk, files
collecting. The following command gets the file "/tmp/message.txt" from each remote host and copies
it locally to "message-number.txt" where "number" is the logical rank of the source node:
taktuk -s -m host1 -m host2 -m host3
broadcast get [ /tmp/message.txt ] [ message-$rank.txt ]
Ctrl-D
finally, it seems important to mention that "put/get" commands can copy directories and keep files
permissions unchanged.
communication
TakTuk can also be used to establish a point-to-point communication. Assume the file
"communication.pl" contains the following Perl script:
my $rank = TakTuk::get('rank');
my $count = TakTuk::get('count');
if ($rank == 1)
{
print "I'm process 1\n";
if ($count > 1)
{
TakTuk::send(to=>2, body=>"Hello world");
}
}
elsif ($rank == 2)
{
print "I'm process 2\n";
my ($from, $message) = TakTuk::recv();
print "Process $to received $message from $from\n";
}
then the execution of the following command:
taktuk -m localhost -m localhost broadcast taktuk_perl [ - ]\;broadcast input file [ communication.pl ]
would produce an output similar to:
Astaroth.local: taktuk_perl: 3523: output > I'm process 2
Astaroth.local: taktuk_perl: 3523: output > Process 2 received Hello world from 1
Astaroth.local: taktuk_perl: 3523: status > 0
Astaroth.local: taktuk_perl: 3524: output > I'm process 1
Astaroth.local: taktuk_perl: 3524: status > 0
if the file "communication.pl" was placed in the login directory of the user, this could have also
been executed by the more simple:
taktuk -m localhost -m localhost broadcast taktuk_perl [ communication.pl ]
output templates and redirections
TakTuk is also capable of making each site echo its rank without command status information:
taktuk -o status -m host1 -m host2 broadcast exec [ 'echo $TAKTUK_RANK' ]
or removing the prompt before each line of output from commands:
taktuk -o output='"$line\n"' -m host1 -m host2 broadcast exec [ 'echo $TAKTUK_RANK' ]
or even changing the prompt to make it display only the stream type:
taktuk -o default='"$type > $line\n"' -m host1 -m host2 broadcast exec [ 'echo $TAKTUK_RANK' ]
and it also possible to redirect the status to file descriptor 2 only for the second host:
taktuk -m host1 -R status=2 -m host2 broadcast exec [ 'echo $TAKTUK_RANK' ]
and so on...
Developer usage
debugging TakTuk
debugging in TakTuk is made using "debug", "warning" and "error" functions of the package
"diagnostic". These routines, depending on the debugging level of the package in which they are
called, produce an output that is propagated up to the root node and printed on screen.
By default the debugging level of packages is set to 2 (everything is printed out except "debug"
messages). It might be changed for each package using the -D option. For instance the following code
executes "true" on "toto.nowhere.com" and prints out every bit of internal messaging:
taktuk -D default=1 -m toto.nowhere.com broadcast exec [ true ]
but one could have executed the same command keeping only messages from the "scheduler" package:
taktuk -D scheduler=1 -m toto.nowhere.com broadcast exec [ true ]
or ensuring an execution exempted of any warning or error messages:
taktuk -D default=4 -m toto.nowhere.com broadcast exec [ true ]
internal messages server
the internal message server used in TakTuk for the management of logical network construction,
commands execution and I/O forwarding can be exposed using the -r option:
taktuk -r
Notice that in this mode the behavior of TakTuk can seem very cryptic. This is not intended for
ordinary users.
BUGS
The development of TakTuk is still in progress, so there are propably numbers of bugs. For now, the
following characteristics (some of them are not really bugs) have been identified :
hanged commands
currently TakTuk do not quit (even if asked to do so) if some local commands do not terminate upon
the closing of their standard input. Interrupting TakTuk actually terminate the engine but do not
kill these commands. We still have to decide if this is the appropriate behavior.
command order
broadcasts and multicast (set specifications) are not synchronized the same way in TakTuk. Thus,
broadcast commands given after multicast commands might be executed before these last ones. Use the
"synchronize" command to avoid this.
fork failures
this is not really a bug : when a machine is highly loaded, fork may fail. If this happen to a local
command, a distributed application may deadlock, because the taktuk instances numbering is correct
but some instance didn't fork the local command. The simplest fix is to use timeouts on
"TakTuk::recv()".
You might also want to have a look at:
http://taktuk.gforge.inria.fr/Bugs.txt
where all the temporary bugs are listed version by version.
SEE ALSO
taktukcomm(3), TakTuk(3), TakTuk::Pilot(3)
AUTHOR
The original concept of TakTuk has been proposed by Cyrille Martin in his PhD thesis. People involved in
this work include Jacques Briat, Olivier Richard, Thierry Gautier and Guillaume Huard.
The author of the version 3 (perl version) and current maintainer of the package is Guillaume Huard.
COPYRIGHT
TakTuk is provided under the terms of the GNU General Public License version 2 or later.