Integrated: 8267155: runtime/os/TestTracePageSizes times out

[Thomas Stuefe]

On Mon, 17 May 2021 16:09:32 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> This Linux-specific test parses `/proc/self/smaps` using a dotall regular expression. If part of the expression don't match it explodes in complexity, leading to timeouts.
> 
> In our case, `VmFlags` tag was missing from smaps, which was introduced with kernel 3.8. I am actually not able to determine how slow they were; on one machine they ran for two hours before getting killed.
> 
> I tried to fiddle with the regular expression and gave up, instead opting to rewrite the parser to get a simple one-pass scan. This is way faster than before - on our old-kernel machines the tests complete in 2 minutes. On new kernels the test is a bit faster too.
> 
> In addition to rewriting the parser, I added code which copies the smaps file into the test directory before parsing it. I do this to minimize problems should the underlying proc fs content change while parsing, and to have a way to retain the parsed smaps files.
> 
> I also added a way to feed an external smaps file into the test. Of course the test would fail, but it was a way to test the parser.
> 
> Unfortunately, this does not make the test succeed. The timeouts are gone, but we have still have no way to know if TPHs are enabled or not. That is a separate issue though.
> 
> Thanks, Thomas

This pull request has now been integrated.

Changeset: 726785b8
Author:    Thomas Stuefe <stuefe at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/726785b8d7c18569bddae6a08fa7f61d8d7bd2c4
Stats:     133 lines in 1 file changed: 95 ins; 0 del; 38 mod

8267155: runtime/os/TestTracePageSizes times out

Reviewed-by: shade, sjohanss

-------------

PR: https://git.openjdk.java.net/jdk/pull/4064