Edit report at https://bugs.php.net/bug.php?id=79519&edit=1
ID: 79519
Updated by: nikic@php.net
Reported by: kieran at miami-nice dot co dot uk
Summary: Memory leak in PHP 7.4
Status: Open
Type: Bug
Package: Performance problem
Operating System: Linux
PHP Version: 7.4.5
Block user comment: N
Private report: N
New Comment:
I see. The master branch case is still potentially actionable from our side. The problem there is
that GC runs too rarely. PHP 7.4 made this worse, because collecting objects with destructors
requires two GC runs, and is seems Laravel makes use of destructors somewhere in there.
There's probably two things we can do to improve this at least:
1. Count any GC run with destructors as a "successful" run, so threshold is reduced.
2. Allow threshold reductions below the default of 10000, which seems too high for this case.
Alternatively we could always automatically rerun GC if we encountered destructors, instead of
waiting for the next GC run.
Previous Comments:
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[2020-05-15 10:53:42] kieran at supportpal dot com
Can ignore the master branch. That was an issue in Laravel that I pushed a fix for. I've just
not updated that repository yet.
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[2020-05-15 10:45:39] nikic@php.net
It looks like the cause for the "routes" case is the same. However, the "master"
branch is a different issue. Here are the massif outputs for 7.3 and 7.4: https://gist.github.com/nikic/2a5d1a6eb4a4bb82be5e18225ae16d87
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[2020-05-15 09:22:42] nikic@php.net
@kieran: PHP 7.4 fixed some issues related to anonymous functions "overwriting" previous
anonymous functions in the same file under some circumstances. Unfortunately this also means that
this leak is now more pronounced, because this accidental destruction vector no longer exists.
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[2020-05-15 09:16:40] kieran at supportpal dot com
I thought it might be that too, but it seems odd that 7.4 is so much higher when that bug report
suggests the issue exists in most of 7.x
Nothing in the ms_print in my previous message?
I'll check if includes can be memorised.
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[2020-05-15 08:54:12] nikic@php.net
@kieran: The "factories" case looks like https://bugs.php.net/bug.php?id=76982, where a
file declaring an anonymous function is included many times. The anonymous function declaration will
leak in that case. This is a bug in PHP, but not one that will be fixed in 7.4. I'm not
familiar with Laravel's factory system, but it can probably be addressed there by making that
the includes are memoized.
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