[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Alexey Izbyshev]

Alexey Izbyshev  added the comment:

I've encountered this issue too. My use case was a 32-bit Python on a 64-bit 
CentOS system, and my understanding of the issue was that 64-bit libgcc_s is 
somehow counted as a "provider" of libgcc_s for 32-bit libc by the package 
manager, so 32-bit libgcc_s is never installed even when "yum install 
glibc.i686" is used because everything seems "already OK":

$ yum deplist glibc

...
  dependency: libgcc
   provider: libgcc.x86_64 4.1.2-55.el5
   provider: libgcc.i386 4.1.2-55.el5
...

(The above is for CentOS 5, but at the time I tested 6 and 7 as well, with the 
same result).

But I suggest not to dismiss this issue as a packaging bug. Glibc needs 
libgcc_s for pthread_exit() because it's implemented in terms of 
pthread_cancel(), and the latter wants to do stack unwinding (probably to 
cleanup resources for each stack frame). But the code for unwinding lives in 
libgcc_s. The non-intuitive thing here is that glibc tried to optimize this 
dependency by dlopen'ing libgcc_s when pthread_cancel() is called instead of 
making it a startup dependency. Many people consider this a terrible design 
choice since your program can now fail at an arbitrary moment due to dlopen() 
failure (and missing libgcc_s is not the only possible reason[1]).

Since CPython doesn't use pthread_cancel() directly, I propose a simple 
solution  -- just `return NULL` from thread functions instead of calling 
pthread_exit(). The last time I looked, pthread_exit() in CPython is only 
called from top frames of the threads, so a direct `return` should suffice. If 
the top-level thread function simply returns, no stack unwinding is needed, so 
glibc never uses its cancellation machinery.

I've tested that this solution worked at the time (for 3.8 I think), and the 
test suite passed. If there is interest in going this way, I can test again.

[1] https://www.sourceware.org/bugzilla/show_bug.cgi?id=13119

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nosy: +izbyshev

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Christian Heimes]

Christian Heimes  added the comment:

It might be a packaging or documentation issue. I'm assiging the ticket to 
Matthias. He is the Debian and Ubuntu package maintainer.

--
assignee:  -> doko
nosy: +doko

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Xinmeng Xia]

Xinmeng Xia  added the comment:

>>uname -a
Linux xxm-System-Product-Name 4.15.0-64-generic #73~16.04.1-Ubuntu SMP Fri Sep 
13 09:56:18 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

>>uname -r
4.15.0-64-generic


>>lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:Ubuntu 16.04.3 LTS
Release:16.04
Codename:   xenial

I download Python from https://www.python.org/downloads/. Then I extract it,run 
install command ./configure,make,sudo make install. I also try the versions of 
Python 3.5-3.10 and even cPython on GitHub. The results are the same. But when 
I try this program on Python 2, the program will not cause core dump. I think 
Python 2 is initially installed with the system, not by me. So I guess no link 
is referred to libgcc_s.so.1 when I install new version of Python.

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Christian Heimes]

Christian Heimes  added the comment:

Please provide more information. What Linux distribution and distro version are 
you using? How did you install Python?

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Xinmeng Xia]

Xinmeng Xia  added the comment:

>>python310 -V
Python 3.10.0a2

>>uname -v
#73~16.04.1-Ubuntu SMP Fri Sep 13 09:56:18 UTC 2019

Thank you!

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Christian Heimes]

Christian Heimes  added the comment:

What's your platform and distribution?

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[issue42888] Not installed “libgcc_s.so.1” causes parser crash.

[Xinmeng Xia]

New submission from Xinmeng Xia :

The following thread program will cause Python3.10 parser "core dump" due to 
missing “libgcc_s.so.1”. "pthread_cancel" cannot work correctly. I am wondering 
is there any possible to install or link to libgcc_s.so.1 during Python 
installation?

===
import socket
from threading import Thread
class thread(Thread):
  def run(self):
  for res in socket.getaddrinfo('www.google.com',8080):
  sock = socket.socket()
  sock.connect(res[4])

for i in range(2000):
thread().start()

Error message:
---

Exception in thread Thread-1346:
Traceback (most recent call last):
  File "/usr/local/python310/lib/python3.10/threading.py", line 960, in 
_bootstrap_inner
  File "/usr/local/python310/lib/python3.10/threading.py", line 960, in 
_bootstrap_inner
Exception in thread Thread-1172:
Traceback (most recent call last):
...
Exception in thread Thread-1509:
Exception in thread Thread-1510:
libgcc_s.so.1 must be installed for pthread_cancel to work
Exception in thread Thread-1511:
Traceback (most recent call last):
Aborted (core dumped)
---

--
components: Interpreter Core
messages: 384798
nosy: xxm
priority: normal
severity: normal
status: open
title: Not installed “libgcc_s.so.1” causes parser crash.
type: crash
versions: Python 3.10

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