[PATCH] D122251: [lit] Use sharding for GoogleTest format

[Yuanfang Chen via Phabricator via llvm-commits]

ychen added a comment.

In D122251#3491815 <https://reviews.llvm.org/D122251#3491815>, @probinson wrote:

>> The buildbot totals are counting the number of shards across all unit tests. The summary at the end of the log is counting the number of test cases like before.
>
> lit used to report (or include in the report) the number of individual test functions across all the unittests.  Now I believe it is reporting the number of shards, instead?  I should think the code in lit that parses googletest output should be able to extract the number of tests executed by each shard (and if not, it could be upgraded to do so).  That would recover the number that people have been expecting to see (both directly from lit, from buildbots, and possibly from metrics recorded elsewhere).

Yeah, I attempted this before posting the patch. It is not trivial. There is one shared results vector across all individual jobs in the thread pool and the LIT thread pool is multiprocess instead of multithreaded. Extracting the results inside a shard earlier would incur some nontrivial overhead due to IPC and from my initial attempt, the required source code changes are pretty intrusive so I ended up deferring the shard results extraction until the test reporting phase (which is after the thread pool execution is done.)


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