[ruby-core:71588] [Ruby trunk - Bug #11692] [PATCH] Re-enable GC if stack overflow was caught from signal handler

[ko1@atdot.net]

Issue #11692 has been updated by Koichi Sasada.


Unfortunately, it is known problem (2nd time machine stack overflow we can not capture correctly).

* 1st machine stack overflow
  * SEGV
  * check machine stack overflow
  * raise an error from signal handler (*1) by longjmp.
* 2nd machine stack overflow
  * SEGV
  * signal status is signaling. So OS can not deliver signal correctly...

The correct way is restoring signal status using sigsetjmp/siglongjmp at (*1).
However, on Linux 2.x, siglongjmp is too slow than longjmp, so that we continue to use longjmp, at least the last time we had discussed this issue. We can't slow down Ruby interpreter for such a corner case.

However, Linux 2.x is older OS. So that we can change.
(BTW, I'm using Linux 2.6 on several machines)


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Bug #11692: [PATCH] Re-enable GC if stack overflow was caught from signal handler
https://bugs.ruby-lang.org/issues/11692#change-54971

* Author: Alex Gaziev
* Status: Closed
* Priority: Normal
* Assignee: Koichi Sasada
* ruby -v: 
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
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We got ruby application running on our production server and noticed that it regularly crashes with out of memory errors.
After months of investigation, I narrowed the case to the examples (1/2). 
After digging ruby sources and running test code, I found out that GC stopped working after recovering from native stack overflow error.
Probably the relevant code appeared in 2.2 https://github.com/ruby/ruby/commit/0c391a55d3ed4637e17462d9b9b8aa21e64e2340
where ruby_disable_gc_stress became ruby_disable_gc.

Patches for trunk and 2.2 branches below.

---Files--------------------------------
example1.rb (311 Bytes)
example2.rb (333 Bytes)
re-enable-gc-after-stackoverflow-trunk.patch (985 Bytes)
re-enable-gc-after-stackoverflow-ruby-2-2.patch (985 Bytes)
gc_threads_issue.rb (1.53 KB)


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