Manual: ustat

ustat(8)					   System Manager's Manual					    ustat(8)

NAME
       ustat,  javastat,  nodestat,  perlstat,	phpstat, pythonstat, rubystat, tclstat - Activity stats from high-level lan‐
       guages.

SYNOPSIS
       javastat [-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]]
       perlstat [-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]]
       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]]
       tclstat [-C] [-S {cload,excp,gc,method,objnew,thread}] [-r MAXROWS] [-d] [interval [count]]
       ustat [-l {java,node,perl,php,python,ruby,tcl}] [-C] [-S {cload,excp,gc,method,objnew,thread}] [-r MAXROWS] [-d] [in‐
       terval [count]]

DESCRIPTION
       This is "top" for high-level language events, such as garbage collections, exceptions, thread creations, object allo‐
       cations, 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. Not all language runtimes provide the same set of details.

       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 Java, Node, Perl, PHP, Python, Ruby,
       and Tcl. 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,node,perl,php,python,ruby,tcl}
	      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)

USER COMMANDS						 2018-10-09						    ustat(8)