( )⚙ D397 arc: fix performance of "arc unit" with vanilla arcanist

This is an archive of the discontinued Mercurial Phabricator instance.

Differential D397

arc: fix performance of "arc unit" with vanilla arcanist
ClosedPublic

Authored by simpkins on Aug 14 2017, 10:48 PM.
Tags
None
Subscribers
None

Details

Reviewers
stash
ryanmce
quark
Group Reviewers
Restricted Project
Commits
rFBHGX6816754eb0f8: arc: fix performance of "arc unit" with vanilla arcanist
Summary

The upstream phacility libphutil code sets the PHP "xdebug.max_nesting_level"
config setting to PHP_INT_MAX. When using HHVM this turns on XDebug profiling,
which appears to make things substantially slower, particularly on Linux.

This was making "arc unit" take substantially longer, and even caused test
failures in some cases. (For instance, some tests check for messages saying
that hg obtained the lock after 1 second, but this can take substantially
longer than 1 second with XDebug profiling enabled.)

Resetting xdebug.max_nesting_level back to 0 turns profiling back off again,
and fixes the performance issues.

Test Plan

Ran arc unit and confirmed that it ran in roughly the same time as running
scripts/unit.py manually.

Diff Detail

Repository
rFBHGX Facebook Mercurial Extensions
Branch
default
Lint
Lint OK
Unit
Unit Tests OK

Event Timeline

simpkins created this revision.Aug 14 2017, 10:48 PM
Herald added a reviewer: Restricted Project. · View Herald TranscriptAug 14 2017, 10:48 PM
quark accepted this revision.Aug 15 2017, 12:06 AM
This revision is now accepted and ready to land.Aug 15 2017, 12:06 AM
ryanmce edited edge metadata.Aug 15 2017, 3:42 AM

Wow, awesome debugging!

Closed by commit rFBHGX6816754eb0f8: arc: fix performance of "arc unit" with vanilla arcanist (authored by simpkins). · Explain WhyAug 16 2017, 11:18 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 903

.hgarcanist/__phutil_library_init__.php

<?php <?php
phutil_register_library('fb-hgext-arcanist', __FILE__); phutil_register_library('fb-hgext-arcanist', __FILE__);
// When running under HHVM, reset xdebug.max_nesting_level to 0
// This is unfortunately set to PHP_INT_MAX in
// libphutil/scripts/__init_script__.php
//
// With HHVM setting xdebug.max_nesting_level to a non-zero value automatically
// turns on XDebug profiling. This makes many things substantially slower, and
// appears to even affect non-PHP children processes spawned by this process.
if (defined('HHVM_VERSION')) {
ini_set('xdebug.max_nesting_level', 0);
}