There is limited support for detecting race conditions in multithreaded NaCl programs, as well as in NaCl trusted code. You can debug either untrusted or trusted code in each program run, not both at the same time.
Please note, that debugging untrusted code with ThreadSanitizer is a work in progress. We don't yet support some synchronization primitives, and will produce false race reports when they are used.
As with Memcheck, only x86_64 is supported at the moment.
Currently, ThreadSanitizer for NaCl is supported only on Linux x86_64. From native_client directory you can run it like this: ./scons --mode=nacl,dbg-linux platform=x86-64 sdl=none \ run_under=src/third_party/valgrind/bin/tsan.sh,--suppressions=src/third_party/valgrind/nacl.supp,--ignore=src/third_party/valgrind/nacl.ignore,--nacl-untrusted,--error-exitcode=1 \ scale_timeout=20 running_on_valgrind=True with_valgrind=True tsan_bot_tests
run_under allows you to pass the name of the tool under which you want to run tests. If the tool has options, pass them after comma: ‘tool,--opt1,--opt2’. (the tool name and the parameters can not contain commas)scale_timeout=20 multiplies all timeouts by 20 (Remember, valgrind is slow!).running_on_valgrind=True modifies test behaviour in a way suitable for Valgrind: reduce iteration count for long loops, disable some tests.with_valgrind=True links an untrusted Valgrind module to the test binary. This will hopefully not be needed when NaCl supports dynamic linking.src/third_party/valgrind/bin/tsan.sh is a modified Valgrind/ThreadSanitizer binary which can run on NaCl.--log-file=<file_name>: put warnings to a file instead of stderr.--error-exitcode=<N>: if at least one warning is reported, exit with this error code (by default, valgrind uses the program's exit code)--nacl-untrusted enables debugging untrusted code. Omit this option if you want to debug the trusted parts.For more info on ThreadSanitizer, visit http://code.google.com/p/data-race-test/wiki/ThreadSanitizer.
There is a shorter alias for all these options: ./scons --mode=dbg-linux,nacl sdl=none platform=x86-64 sdl=none buildbot=tsan tsan_bot_tests
We disable handling of synchronization and memory events coming from either untrusted or trusted code depending on the --nacl-untrusted option.
Also see [Memcheck/NaCl implementation details] (http://code.google.com/p/nativeclient/wiki/ValgrindMemcheck#Implementation_details).