Design documentIt is on its own page. General informationtrace_inputs.py and trace_test_cases.py are tools to respectively trace any executable or specifically a google-test executable. They report each child processes, their command line, initial current working directory, exit code, each file accessed per each child process in an hierarchical format. This is useful to get data about the amount of files read by each executable and get an idea of how many files are access by each of the processes, including child processes. It is good to know the amount of short-lived child processes that are created.This is especially frightening to trace browser_tests. The output format is in json, so it can be easily consumed by a webpage, and is formatted in an OS-independent way as much as possible. OS-specific tracer limitations may limit the amount of information; dtrace has issues tracing the command line and the Windows NT Kernel tracer doesn't trace the initial working directory, because there is no such thing at the kernel level; the current working directory is purely a user-mode implementation on Windows. If you are looking to generate .isolate files, you are at the wrong place. The scripts below are used as libraries by the higher level scripts documents in the test isolation page.trace_inputs.pyBackgroundtrace_inputs.py runs an executable, let it be Chrome itself or an unit test and uses strace on linux, dtrace* on mac or NT Kernel Logger** on windows to log all the files that were opened or touched. It generates an OS-specific file that can be read to generate a JSON file. * dtrace requires root password on OSX. you can work around with setuid or visudo but there are security-related implications. ** logman.exe requires elevated command prompt. Its the slowest of the three. Normal workflowIn general, you will run it twice to generate a json file. First to trace it, second to read and analyse the traces generated by the tracer and output a json file. python tools/swarm_client/trace_inputs.py trace -l log_file out/Release/foo_testspython tools/swarm_client/trace_inputs.py read -l log_file --root-dir . --jsonSubcommandscleanclean deletes all the logs properly.python tools/swarm_client/trace_inputs.py clean -l log_filehelphelp prints information about a specific subcommand.python tools/swarm_client/trace_inputs.py help tracereadread reads a trace previously generated with trace. The example below will strip any file accessed outside of --root-dir to reduce noise and will replace any path with the corresponding variable with --variable. Variables are useful to abstract difference with the OS or the build tool, like abstracting the build output directory.python tools/swarm_client/trace_inputs.py read -l log_file -V PRODUCT_DIR out/Release --root-dir /home/$USER/chrome/src --jsontracetrace executes an executable under the tracer and generates a new trace log. It doesn't output any information. Use read to read the trace.python tools/swarm_client/trace_inputs.py trace -l log_file out/Release/base_unittestsExampleTo generate a log and then read it: python tools/swarm_client/trace_inputs.py trace --log out/Release/net_unittests.results.log \ testing/xvfb.py out/Release out/Release/net_unittestsxvfb.py is a wrapper script to start XVFB on linux and is a no-op on other platforms. Any previous log is overwritten.trace_test_cases.pyTakes a given google-test executable and traces all of the tests (running them individually). trace_inputs.py read must be used to read the trace back. The difference between this and trace_inputs.py trace is that trace_inputs.py runs all the tests in the executable serially under a single trace, while trace_test_cases.py runs one executable per CPU core, configurable with --jobs, and traces each test case individually. The end result is that trace_test_cases.py is generally faster than trace_inputs.py.Use --help for more information.ExampleRuns 1% of the test cases by selecting shard 0 of 100 shards and read the logs python tools/swarm_client/trace_test_cases.py --index 0 --shards 100 out/Release/net_unittests |
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Tracing tools |