arthas/arthas-tutorials-en/command/profiler/profiler.md

Generate a flame graph using async-profiler

profiler command supports generate flame graph for application hotspots.

The basic usage of the profiler{{}} command is profiler action [actionArg]{{}}

View all supported actions

profiler actions{{execute T2}}

View version

profiler version{{execute T2}}

Start profiler

profiler start --event cpu{{execute T2}}

By default, the sample event is cpu{{}} . Can be specified with the --event{{}} parameter.

Get the number of samples collected

profiler getSamples{{execute T2}}

View profiler status

profiler status{{execute T2}}

Stop profiler

Generating html format results

By default, the result file is html{{}} format. You can also specify it with the --format{{}} parameter:

profiler stop --format html{{execute T2}}

Or use the file name name format in the --file{{}} parameter. For example, --file /tmp/result.html{{}} .

profiler stop --file /root/arthas-output/result.html{{execute T2}}

View profiler results under arthas-output via browser

By default, arthas uses http port 8563, click to open and enter username arthas and password arthas to view the arthas-output{{}} directory below Profiler results:

Click to view specific results:

Profiler supported events

profiler list{{execute T2}}

Under different platforms and different OSs, the supported events are different. For example, under macos:

$ profiler list
Basic events:
  cpu
  alloc
  lock
  wall
  itimer

Under linux

$ profiler list
Basic events:
  cpu
  alloc
  lock
  wall
  itimer
Perf events:
  page-faults
  context-switches
  cycles
  instructions
  cache-references
  cache-misses
  branches
  branch-misses
  bus-cycles
  L1-dcache-load-misses
  LLC-load-misses
  dTLB-load-misses
  mem:breakpoint
  trace:tracepoint

If you encounter the permissions/configuration issues of the OS itself and then missing some events, you can refer to the async-profiler documentation.

You can use the --event{{}} parameter to specify the event to sample, such as sampling the alloc{{}} event:

profiler start --event alloc{{execute T2}}

Resume sampling

profiler resume{{execute T2}}

The difference between start{{}} and resume{{}} is: start{{}} is the new start sampling, resume{{}} will retain the data of the last stop{{}} .

You can verify the number of samples by executing profiler getSamples{{}} .

Use execute{{}} action to execute complex commands

profiler execute 'start,framebuf=5000000'{{execute T2}}

For example, start sampling:

profiler execute 'start,framebuf=5000000'{{execute T2}}

Stop sampling and save to the specified file:

profiler execute 'stop,file=/root/arthas-output/result.html'{{execute T2}}

Specific format reference: arguments.cpp