SEGFAULTs consistently happening on CI

[lcobucci]

On #737 (review), @asgrim mentions that SEGFAULTs are constantly haunting this project.

I've done some digging around and managed to reproduce the issue!

Although I couldn't pinpoint exactly the problem (on the timebox I've allocated for this), it seems related to Psl\Shell\execute() and PHPUnit ANSI's formatter (when under a very specific environment).

The main trigger, though, is @Ocramius' good old friend: lack of Git's safe.directory configuration 😬

We can use Docker to reproduce the SEGFAULTs.
I've done with the following Dockerfile:

FROM ubuntu:latest

ENV DEBIAN_FRONTEND noninteractive

RUN apt-get update \
    && apt-get install -y --reinstall software-properties-common \
    && add-apt-repository -y ppa:ondrej/php \
    && apt-get install -y php8.1  php8.1-bz2 php8.1-cli php8.1-common php8.1-curl php8.1-dev php8.1-intl php8.1-mbstring php8.1-opcache php8.1-phpdbg php8.1-readline php8.1-xml  php8.1-zip php8.1-bcmath gdb libxml2-utils git

COPY --from=composer /usr/bin/composer /usr/bin/composer

CMD ["/bin/sh", "-c", "composer install && xmllint --schema vendor/phpunit/phpunit/phpunit.xsd phpunit.xml.dist && vendor/bin/phpunit"]

Then, we can see the problem after executing the following commands on the root dir of this project (against the latest commit of 8.4.x):

$ docker build -t bc-segfault-test . && docker run --rm -it -v $(pwd):/app -w /app bc-segfault-test

The "fun" begins when we start playing with the commands...
For example, no SEGFAULT happens when running any of these (after the previous commands):

$ docker run --rm -it -v $(pwd):/app -w /app bc-segfault-test vendor/bin/phpunit --testdox
$ docker run --rm -it -v $(pwd):/app -w /app bc-segfault-test vendor/bin/phpunit --colors=never
$ docker run --rm -v $(pwd):/app -w /app bc-segfault-test vendor/bin/phpunit
$ docker run --rm -it -v $(pwd):/app -w /app bc-segfault-test /bin/bash -c "git config --global --add safe.directory /app && vendor/bin/phpunit"

GBD

We can also use that image to play with GDB:

$ docker run --rm -it -v $(pwd):/app -w /app bc-segfault-test gdb php
GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from php...
(No debugging symbols found in php)
(gdb) run vendor/bin/phpunit
Starting program: /usr/bin/php vendor/bin/phpunit
warning: Error disabling address space randomization: Operation not permitted
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
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PHPUnit 9.5.27 by Sebastian Bergmann and contributors.

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Program received signal SIGSEGV, Segmentation fault.
0x00005593d581241b in zend_unfinished_execution_gc ()
(gdb) bt
#0  0x00005593d581241b in zend_unfinished_execution_gc ()
#1  0x00005593d5849f1b in ?? ()
#2  0x00005593d582e758 in zend_gc_collect_cycles ()
#3  0x00005593d582d517 in ?? ()
#4  0x00005593d58162ad in execute_ex ()
#5  0x00005593d57a14b4 in zend_call_function ()
#6  0x00005593d5849c12 in ?? ()
#7  0x00005593d584ac32 in ?? ()
#8  0x00005593d57480f7 in make_fcontext ()
#9  0x0000000000000000 in ?? ()

Changing the logic in Roave\BackwardCompatibility\Git\GitParseRevision to use exec() instead of Psl\Shell\execute() does remove the issue too, though I don't think that's the direction you want to go.

With all that said, I hope this helps @asgrim @Ocramius or @azjezz to investigate further and decide what you want to do to solve the SEGFAULTs.

[Ocramius]

Likely an issue with how PSL executes commands here? It has support for async dispatch, so it may be hidden in its internals.

Anyway, safe.directory=* is safe in docker contexts, so we'd need to adjust that too :D

[lcobucci]

It's interesting to see that disabling the ANSI output seems to prevent the SEGFAULTs.

Perhaps that's a good first step until the root cause is addressed.

I also didn't test if upgrading to PHPUnit 10 has any impact.

[lcobucci]

I just noticed that this project relies on ghcr.io/laminas/laminas-continuous-integration:1 to run CI, which already solves the safe.directory=*

Sooo, all my comments are kind of moot points, yay 🎉

Running the following command does give me a SEGFAULT:

docker run -it --rm \
  -w /github/workspace  -e GITHUB_ACTIONS=true -e CI=true \
  -v $(pwd):/github/workspace ghcr.io/laminas/laminas-continuous-integration:1 "{\"command\":\"./vendor/bin/phpunit\",\"php\":\"8.1\",\"extensions\":[\"dom\",\"json\",\"libxml\",\"simplexml\",\"bcmath\"],\"ini\":[\"memory_limit=-1\"],\"dependencies\":\"latest\",\"ignore_platform_reqs_8\":false,\"ignore_php_platform_requirement\":false,\"additional_composer_arguments\":[],\"before_script\":[\"xmllint --schema vendor/phpunit/phpunit/phpunit.xsd phpunit.xml.dist\"]}"

Let me check a bit more 👍

[lcobucci]

Okay, I investigated a bit more and found out that:

1. Issue has nothing to do with the safe.directory crap
2. Issue has 100% to do with PSL usage of proc_open in combination with PHPUnit's default printer (ANSI or not)
3. PHPUnit 10.0 ships new stuff that makes the problem go away...

I´m sending a patch to upgrade it that should solve this 😁

[azjezz]

Sorry for being late to the party :D

Issue has 100% to do with PSL usage of proc_open

is the issue just with PSL, or proc_open in general? 🤔 i need to do a bit more investigation to see what is going on here, but it seems really strange.

[lcobucci]

Sorry for being late to the part :D

Issue has 100% to do with PSL usage of proc_open

is the issue just with PSL, or proc_open in general? thinking i need to do a bit more investigation to see what is going on here, but it seems really strange.

I think is proc_open + PHPUnit but I haven't tried to isolate things more.

[azjezz]

it seems to be an issue in revolt event loop when using PHP 8.1.15-16 and 8.2.2-3, can you make sure that you are using at least 8.2.4 or 8.1.17?

[Ocramius]

Yes, although I'd need to release the Laminas CI container first again