From: "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...> Date: 2013-11-06T07:19:49+09:00 Subject: [ruby-core:58181] [ruby-trunk - Bug #9082] popen3 hangs when stderr gets lots of output Issue #9082 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas). At least with the block form. I think this should be documented if this is the case. ---------------------------------------- Bug #9082: popen3 hangs when stderr gets lots of output https://bugs.ruby-lang.org/issues/9082#change-42767 Author: rosenfeld (Rodrigo Rosenfeld Rosas) Status: Rejected Priority: Normal Assignee: Category: lib Target version: ruby -v: ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-linux] Backport: Create this program test.rb: STDERR.puts "some error line\n" * 10_000 Then, try this: ruby -r open3 -e "Open3.popen3('ruby test.rb'){|i,o,e,t|i.close;o.read}" For this particular case, if I do "e.read" before "o.read" it works. But for my real case involving the "tidy" command with lots of warnings in the stderr it will freeze even if I call "e.read". Since I don't really need this output, I'm using popen2 and redirecting stderr to /dev/null, so this is not urgent, but I thought you'd like to know about this. Also, if you replace 10_000 with 1_000 above it also works here. -- http://bugs.ruby-lang.org/