Bug #20231: Don't wait in io_binwrite_string if not necessary.

• Status: Closed
• Assignee: ioquatix (Samuel Williams)
• Target version: -
• Backport: 3.2: DONE, 3.3: DONE

[ioquatix (Samuel Williams)]

PR: https://github.com/ruby/ruby/pull/9792

Writing to a buffered IO can result in the entire internal buffer being flushed, which causes io_binwrite_string_internal to return 0. In that case, we were setting errno = EAGAIN. This causes rb_io_maybe_wait_writable to be invoked, however we should immediately retry io_binwrite_string_internal instead.

The reason why calling rb_io_maybe_wait_writable is a bad idea in general, is that not all IO can go via this mechanism in every situation - in other words, kqueue does not support kevent("/dev/null", writable) and returns errno=22 EINVAL. The same applies to some kinds of pipes, TTYs, etc.

Indirectly responsible for https://github.com/socketry/async/issues/301.

[ioquatix (Samuel Williams)]

• Assignee set to ioquatix (Samuel Williams)

[ioquatix (Samuel Williams)]

• Status changed from Open to Closed

[naruse (Yui NARUSE)]

Merging into 3.3 but failed
https://github.com/ruby/ruby/pull/9813

[ioquatix (Samuel Williams)]

@naruse (Yui NARUSE) That PR seems unrelated, is the link correct?

[naruse (Yui NARUSE)]

ioquatix (Samuel Williams) wrote in #note-4:

@naruse (Yui NARUSE) That PR seems unrelated, is the link correct?

Thanks, the correct PR is https://github.com/ruby/ruby/pull/9831

[naruse (Yui NARUSE)]

• Backport changed from 3.2: REQUIRED, 3.3: REQUIRED to 3.2: REQUIRED, 3.3: DONE

ruby_3_3 2c365e6dfb95e0df24725c6f377b9cdf5e354557 merged revision(s) 2554c5d3b8738a248cedb2fea96dfab9fbe19417.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 3.2: REQUIRED, 3.3: DONE to 3.2: DONE, 3.3: DONE

ruby_3_2 bf6e9299ef4f10dbd23f32331c355ac875bfb5e3 merged revision(s) 2554c5d3b8738a248cedb2fea96dfab9fbe19417.

[ioquatix (Samuel Williams)]

Thanks!