Bug #4680

[PATCH] io.c: fix busy wait with sendfile()

Added by Eric Wong almost 3 years ago. Updated almost 3 years ago.

[ruby-core:36150]
Status:Closed
Priority:Normal
Assignee:Akira Tanaka
Category:core
Target version:1.9.3
ruby -v:ruby 1.9.3dev (2011-05-11 trunk 31521) [x86_64-linux] Backport:

Description

io.c: fix busy wait with sendfile()

When combined with a non-blocking descriptor for sendfile(),
select() is used improperly to wait on the writer in the
read FD set along with the reader.

This causes select() to return immediately if src_fd is a
regular file and select() always returns immediately for regular
files (at least under Linux).

Thus, we need to wait on the writer independently of the reader.
Under Linux, we know the reader must must be a regular file if
sendfile() is to be used so we avoid waiting on the reader.

Test script attached maxes out my CPU.

0001-io.c-fix-busy-wait-with-sendfile.patch Magnifier (2.82 KB) Eric Wong, 05/13/2011 05:45 AM

copy_stream_false_select.rb Magnifier (456 Bytes) Eric Wong, 05/13/2011 05:45 AM


Related issues

Related to ruby-trunk - Bug #4683: [PATCH] io.c: copy_stream execute interrupts and retry Closed 05/13/2011

History

#1 Updated by Eric Wong almost 3 years ago

Eric Wong normalperson@yhbt.net wrote:

Test script attached maxes out my CPU.

And with this I also noticed signals aren't handled gracefully
with IO.copy_stream. Fixing now.

--
Eric Wong

#2 Updated by Eric Wong almost 3 years ago

Eric Wong normalperson@yhbt.net wrote:

Eric Wong normalperson@yhbt.net wrote:

Test script attached maxes out my CPU.

And with this I also noticed signals aren't handled gracefully
with IO.copy_stream. Fixing now.

Reported separately: http://redmine.ruby-lang.org/issues/4683

--
Eric Wong

#3 Updated by Yui NARUSE almost 3 years ago

  • Status changed from Open to Assigned
  • Assignee set to Akira Tanaka

#4 Updated by Akira Tanaka almost 3 years ago

  • Status changed from Assigned to Closed

Also available in: Atom PDF