NAME

       ustat,  javastat, pythonstat, rubystat, nodestat, phpstat - Activity stats from high-level
       languages.

SYNOPSIS

       javastat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]  [-d]  [interval
       [count]]
       pythonstat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS] [-d] [interval
       [count]]
       rubystat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]  [-d]  [interval
       [count]]
       nodestat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]  [-d]  [interval
       [count]]
       phpstat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]  [-d]   [interval
       [count]]
       ustat  [-l {java,python,ruby,node,php}] [-C] [-S {cload,excp,gc,method,objnew,thread}] [-r
       MAXROWS] [-d] [interval [count]]

DESCRIPTION

       This is "top" for high-level language events, such  as  garbage  collections,  exceptions,
       thread  creations,  object  allocations, method calls, and more. The events are aggregated
       for each process and printed in a top-like table, which can be sorted by various fields.

       This uses in-kernel eBPF maps to store per process summaries for efficiency.

       This tool relies on USDT probes embedded in many high-level languages, such as Node, Java,
       Python, Ruby, and PHP. It requires a runtime instrumented with these probes, which in some
       cases requires building from source with a USDT-specific flag, such  as  "--enable-dtrace"
       or "--with-dtrace". For Java, some probes are not enabled by default, and can be turned on
       by running the Java process with the "-XX:+ExtendedDTraceProbes" flag. For PHP  processes,
       the environment variable USE_ZEND_DTRACE must be set to 1.

       Newly-created  processes  will  only  be traced at the next interval. If you run this tool
       with a short interval (say, 1-5 seconds),  this  should  be  virtually  unnoticeable.  For
       longer  intervals,  you  might  miss processes that were started and terminated during the
       interval window.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -l {java,python,ruby,node,php}
              The language to trace. By default, all languages are traced.

       -C     Do not clear the screen between updates.

       -S {cload,excp,gc,method,objnew,thread}
              Sort the output by the specified field.

       -r MAXROWS
              Do not print more than this number of rows.

       -d     Print the resulting BPF program, for debugging purposes.

       interval
              Interval between updates, seconds.

       count  Number of interval summaries.

EXAMPLES

       Summarize activity in high-level languages, 1 second refresh:
              # ustat

       Don't clear the screen, and top 8 rows only:
              # ustat -Cr 8

       5 second summaries, 10 times only:
              # ustat 5 10

FIELDS

       loadavg
              The contents of /proc/loadavg

       PID    Process ID.

       CMDLINE
              Process command line (often the second and following arguments will give you a hint
              as to which application is being run.

       METHOD/s
              Count of method invocations during interval.

       GC/s   Count of garbage collections during interval.

       OBJNEW/s
              Count of objects allocated during interval.

       CLOAD/s
              Count of classes loaded during interval.

       EXC/s  Count of exceptions thrown during interval.

       THR/s  Count of threads created during interval.

OVERHEAD

       When  using this tool with high-frequency events, such as method calls, a very significant
       slow-down can be expected. However, many of the high-level languages covered by this  tool
       already  have  a  fairly  high  per-method  invocation  cost,  especially  when running in
       interpreted mode. For the lower-frequency events, such as garbage  collections  or  thread
       creations,  the  overhead  should  not  be  significant.  Specifically,  when probing Java
       processes and not using the "-XX:+ExtendedDTraceProbes" flag, the  most  expensive  probes
       are not emitted, and the overhead should be acceptable.

SOURCE

       This is from bcc.

              https://github.com/iovisor/bcc

       Also  look  in  the  bcc distribution for a companion _example.txt file containing example
       usage, output, and commentary for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Sasha Goldshtein

SEE ALSO

       trace(8), argdist(8), tplist(8)