bcc-javastat(8)

1ustat(8)                    System Manager's Manual                   ustat(8)
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NAME

6       ustat,  javastat,  nodestat,  perlstat,  phpstat, pythonstat, rubystat,
7       tclstat - Activity stats from high-level languages.
8

SYNOPSIS

10       javastat [-C] [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]
11       [-d] [interval [count]]
12       nodestat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}] [-r MAXROWS]
13       [-d] [interval [count]]
14       perlstat [-C] [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]
15       [-d] [interval [count]]
16       phpstat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r MAXROWS]
17       [-d] [interval [count]]
18       pythonstat [-C] [-S {cload,excp,gc,method,objnew,thread}] [-r  MAXROWS]
19       [-d] [interval [count]]
20       rubystat  [-C]  [-S  {cload,excp,gc,method,objnew,thread}] [-r MAXROWS]
21       [-d] [interval [count]]
22       tclstat [-C]  [-S  {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]
23       [-d] [interval [count]]
24       ustat     [-l     {java,node,perl,php,python,ruby,tcl}]     [-C]    [-S
25       {cload,excp,gc,method,objnew,thread}]  [-r  MAXROWS]   [-d]   [interval
26       [count]]
27

DESCRIPTION

29       This  is  "top" for high-level language events, such as garbage collec‐
30       tions, exceptions, thread creations, object allocations, method  calls,
31       and  more.  The events are aggregated for each process and printed in a
32       top-like table, which can be sorted by various fields. Not all language
33       runtimes provide the same set of details.
34
35       This  uses in-kernel eBPF maps to store per process summaries for effi‐
36       ciency.
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38       This tool relies on USDT probes embedded in many high-level  languages,
39       such  as  Java,  Node,  Perl, PHP, Python, Ruby, and Tcl. It requires a
40       runtime instrumented with these probes, which in  some  cases  requires
41       building  from  source  with  a  USDT-specific flag, such as "--enable-
42       dtrace" or "--with-dtrace". For Java, some probes are  not  enabled  by
43       default,  and  can  be  turned  on by running the Java process with the
44       "-XX:+ExtendedDTraceProbes" flag. For PHP  processes,  the  environment
45       variable USE_ZEND_DTRACE must be set to 1.
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47       Newly-created  processes  will  only be traced at the next interval. If
48       you run this tool with a short interval (say, 1-5 seconds), this should
49       be  virtually  unnoticeable.  For longer intervals, you might miss pro‐
50       cesses that were started and terminated during the interval window.
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52       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

55       CONFIG_BPF and bcc.
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OPTIONS

58       -l {java,node,perl,php,python,ruby,tcl}
59              The language to trace. By default, all languages are traced.
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61       -C     Do not clear the screen between updates.
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63       -S {cload,excp,gc,method,objnew,thread}
64              Sort the output by the specified field.
65
66       -r MAXROWS
67              Do not print more than this number of rows.
68
69       -d     Print the resulting BPF program, for debugging purposes.
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71       interval
72              Interval between updates, seconds.
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74       count  Number of interval summaries.
75

EXAMPLES

77       Summarize activity in high-level languages, 1 second refresh:
78              # ustat
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80       Don't clear the screen, and top 8 rows only:
81              # ustat -Cr 8
82
83       5 second summaries, 10 times only:
84              # ustat 5 10
85

FIELDS

87       loadavg
88              The contents of /proc/loadavg
89
90       PID    Process ID.
91
92       CMDLINE
93              Process command line (often the second and  following  arguments
94              will give you a hint as to which application is being run.
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96       METHOD/s
97              Count of method invocations during interval.
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99       GC/s   Count of garbage collections during interval.
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101       OBJNEW/s
102              Count of objects allocated during interval.
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104       CLOAD/s
105              Count of classes loaded during interval.
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107       EXC/s  Count of exceptions thrown during interval.
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109       THR/s  Count of threads created during interval.
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OVERHEAD

112       When  using this tool with high-frequency events, such as method calls,
113       a very significant slow-down can be  expected.  However,  many  of  the
114       high-level  languages  covered  by this tool already have a fairly high
115       per-method invocation cost,  especially  when  running  in  interpreted
116       mode.  For  the  lower-frequency events, such as garbage collections or
117       thread creations, the overhead should not be significant. Specifically,
118       when  probing  Java  processes  and  not  using the "-XX:+ExtendedDTra‐
119       ceProbes" flag, the most expensive probes  are  not  emitted,  and  the
120       overhead should be acceptable.
121

SOURCE

123       This is from bcc.
124
125              https://github.com/iovisor/bcc
126
127       Also  look  in  the  bcc distribution for a companion _example.txt file
128       containing example usage, output, and commentary for this tool.
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OS

131       Linux
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STABILITY

134       Unstable - in development.
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AUTHOR

137       Sasha Goldshtein
138