[ruby-core:92471] [Ruby trunk Bug#15779] After NoMemoryError, ruby freezes and takes 100% CPU

Issue #15779 has been updated by buzztaiki (Taiki Sugawara).

File strace.txt added

In this situation, I want ruby to finish GC quickly or to crash.
In my production code, this issue has been avoided by not creating huge objects and by using rescue and re-raise.


I attach strace log (`strace -ttt -o strace.txt ruby a.rb`).
It seems to cause loop of `Resource temporarily unavailable`.

```
...
1556496315.537693 read(6, 0x55794d88b333, 5) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538029 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538245 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538404 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538524 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538612 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538682 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538751 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538820 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538889 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.538958 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539027 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539094 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539161 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539320 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539401 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
1556496315.539470 read(4, 0x7ffeaf4b5f40, 8) = -1 EAGAIN (Resource temporarily unavailable)
...
```


----------------------------------------
Bug #15779: After NoMemoryError, ruby freezes and takes 100% CPU
https://bugs.ruby-lang.org/issues/15779#change-77819

* Author: buzztaiki (Taiki Sugawara)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-linux]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
Run following reproduce code, ruby freezes and takes 100% CPU.

```
require 'open-uri'

begin
  "a" * 10000000000
ensure
  p open('https://www.ruby-lang.org/')
end
```

But interestingly, the following code does not reproduce this issue.

```
require 'open-uri'

begin
  begin
    "a" * 10000000000
  rescue NoMemoryError
    raise
  end
ensure
  p open('https://www.ruby-lang.org/')
end
```

It was also reproduced when put `sleep 100` in ensure clause, run it and hit Ctrl-C. But `puts 'XXX'` does not reproduce it.


---Files--------------------------------
strace.txt (377 KB)


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