Is there a way to force Bazel to run tests serially

Question

By default, Bazel runs tests in a parallel fashion to speed things up. However, I have a resource (GPU) that can't handle parallel jobs due to the GPU memory limit. Is there a way to force Bazel to run tests in a serial, i.e., non-parallel way?

Thanks.

Answer 1

--jobs 1 will limit the number of parallel jobs Bazel runs to 1.

You can also modify the test targets and add tags = ["exclusive"] to prevent specific test to run in parallel (see http://bazel.io/docs/test-encyclopedia.html).

Answer 2

Use --local_test_jobs=1 to only run a single test job at a time locally.

The max number of local test jobs to run concurrently. Takes an integer, or a keyword ("auto", "HOST_CPUS", "HOST_RAM"), optionally followed by an operation ([-|]) eg. "auto", "HOST_CPUS.5". 0 means local resources will limit the number of local test jobs to run concurrently instead. Setting this greater than the value for --jobs is ineffectual

• tags = ["exclusive"] has other complications to consider with respect to caching.
• --jobs will serialize the entire build process, not just testing, so it's less than ideal.