NAME

       ugc,  javagc,  nodegc,  pythongc,  rubygc  - Trace garbage collection events in high-level
       languages.

SYNOPSIS

       javagc [-h] [-v] [-m] [-M MINIMUM] [-F FILTER] pid
       nodegc [-h] [-v] [-m] [-M MINIMUM] [-F FILTER] pid
       pythongc [-h] [-v] [-m] [-M MINIMUM] [-F FILTER] pid
       rubygc [-h] [-v] [-m] [-M MINIMUM] [-F FILTER] pid
       ugc [-h] [-v] [-m] [-M MINIMUM] [-F FILTER] [-l {java,node,python,ruby}] pid

DESCRIPTION

       This traces garbage collection events as they occur,  including  their  duration  and  any
       additional  information  (such  as  generation  collected  or  type of GC) provided by the
       respective language's runtime.

       This tool relies on USDT probes embedded in many high-level languages, such as Java, Node,
       Python,  and  Ruby.  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".

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

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

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

       -m     Print times in milliseconds. The default is microseconds.

       -M MINIMUM
              Display only collections that are longer than this threshold. The value is given in
              milliseconds. The default is to display all collections.

       -F FILTER
              Display only collections whose textual description matches (contains) this  string.
              The  default  is  to  display  all  collections.  Note  that  the filtering here is
              performed in user-space, and not as part of the BPF program. This means that if you
              have  thousands  of  collection  events, specifying this filter will not reduce the
              amount of data that has to be transferred from the BPF program  to  the  user-space
              script.

       {java,node,python,ruby}
              The language to trace.

       pid    The process id to trace.

EXAMPLES

       Trace garbage collections in a specific Node process:
              # ugc node 148

       Trace garbage collections in a specific Java process, and print GC times in
              milliseconds: # ugc -m java 6004

       Trace garbage collections in a specific Java process, and display them only if
              they  are  longer  than  10ms  and  have  the  string  "Tenured"  in their detailed
              description: # ugc -M 10 -F Tenured java 6004

FIELDS

       START  The start time of the GC, in seconds from the beginning of the trace.

       TIME   The duration of the garbage collection event.

       DESCRIPTION
              The runtime-provided description of this garbage collection event.

OVERHEAD

       Garbage collection events, even if frequent, should not produce  a  considerable  overhead
       when traced because they are still not very common. Even hundreds of GCs per second (which
       is a very high rate) will still produce a fairly negligible overhead.

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), ustat(8), uobjnew(8)