JRuby

Master crashes when calling an FFI-attached C library function

Details

  • Type: Bug Bug
  • Status: Resolved Resolved
  • Priority: Blocker Blocker
  • Resolution: Fixed
  • Affects Version/s: JRuby 1.7.0.pre1
  • Fix Version/s: JRuby 1.7.0.pre1
  • Component/s: Interpreter
  • Labels:
    None
  • Environment:
    OSX 10.6.8, Java7u2
  • Number of attachments :
    0

Description

Download this file. It's a tarball containing 2 gems (ffi-rzmq and zmqmachine) and a C library that is loaded via FFI. There is also a script (install_me) that will ask for sudo permission to install the C lib to /usr/local/lib.

file: http://dl.dropbox.com/u/44434337/jruby_ffi.tgz

After running 'install_me' there will be an unpacked gem directory for zmqmachine.

% cd zmqmachine-0.7.1/examples
% jruby pub_sub.rb

This should result in a spectacular backtrace complaining about a NoMethodError for some FFI function.

https://gist.github.com/ec1065df39561c46b1ff

Interestingly, this same code runs fine on Windows (though the JRuby master is from Friday, 20111216).

Trying to run jruby master with compile.mode=OFF and/or compile.invokedynamic=false has no effect. It still crashes though the backtraces will be different.

The line it crashes on is a call to an FFI-wrapped C function.

Activity

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Chuck Remes added a comment -

BTW, tried to reduce this unsuccessfully. I suspect my attempts to repro a smaller version failed because there is some race condition and/or other moving part that only gets triggered on this more complex project. I can load ffi-rzmq by itself and run the FFI attached functions without incident. Doing the same work via zmqmachine blows it up.

Of course, this all works fine with 1.6.x.

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Chuck Remes added a comment - BTW, tried to reduce this unsuccessfully. I suspect my attempts to repro a smaller version failed because there is some race condition and/or other moving part that only gets triggered on this more complex project. I can load ffi-rzmq by itself and run the FFI attached functions without incident. Doing the same work via zmqmachine blows it up. Of course, this all works fine with 1.6.x.
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Wayne Meissner added a comment - - edited

Chuck, thanks for trying this out.

It is indeed a bug in jffi (the low level lib jruby uses for implementing FFI).

The reason it isn't occurring on windows, is due to optimisations.
i.e. on windows it is:

if (isWindows()) { 
   // use old slow path
} else {
   // generate optimised bytecode/x86 assembly
}

Should be fixed now in jruby-master.

btw, one reason you might not have been able to reproduce on a cut-down codeset is because of the JIT threshold
specifying -Xffi.compile.threshold=1 should make all FFI functions JIT on first use.

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Wayne Meissner added a comment - - edited Chuck, thanks for trying this out. It is indeed a bug in jffi (the low level lib jruby uses for implementing FFI). The reason it isn't occurring on windows, is due to optimisations. i.e. on windows it is: if (isWindows()) { // use old slow path } else { // generate optimised bytecode/x86 assembly } Should be fixed now in jruby-master. btw, one reason you might not have been able to reproduce on a cut-down codeset is because of the JIT threshold specifying -Xffi.compile.threshold=1 should make all FFI functions JIT on first use.
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Chuck Remes added a comment -

Wayne,

a few comments.

1. I did run this test with -Xcompile.mode=OFF and it crashed there too but with a different backtrace (though it ended up at the same Ruby code). Doesn't that disable the JIT which would have avoided the bug you just fixed?

2. Since I posted this JIRA, I did get a crash on Windows in a similar place. Here is the hs_err*.log output: https://gist.github.com/1497411

3. I updated to master on osx and your fix has repaired the issue. I am unable to build a working jruby from my git clone with 'ant dist' so that I can run this on Windows too; the build appears broken (but I don't think it's from your change). As soon as that build recipe is working again I'll try this on Windows.

Show
Chuck Remes added a comment - Wayne, a few comments. 1. I did run this test with -Xcompile.mode=OFF and it crashed there too but with a different backtrace (though it ended up at the same Ruby code). Doesn't that disable the JIT which would have avoided the bug you just fixed? 2. Since I posted this JIRA, I did get a crash on Windows in a similar place. Here is the hs_err*.log output: https://gist.github.com/1497411 3. I updated to master on osx and your fix has repaired the issue. I am unable to build a working jruby from my git clone with 'ant dist' so that I can run this on Windows too; the build appears broken (but I don't think it's from your change). As soon as that build recipe is working again I'll try this on Windows.
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Wayne Meissner added a comment -

Hi Chuck, -Xcompile.mode=OFF works now (i.e. disables FFI stub compilation), so you should be able to reproduce the windows crash on MacOS, assuming it isn't windows specific.

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Wayne Meissner added a comment - Hi Chuck, -Xcompile.mode=OFF works now (i.e. disables FFI stub compilation), so you should be able to reproduce the windows crash on MacOS, assuming it isn't windows specific.
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Charles Oliver Nutter added a comment -

Any update on this, Chuck? Perhaps holidays have kept you away...

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Charles Oliver Nutter added a comment - Any update on this, Chuck? Perhaps holidays have kept you away...
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Chuck Remes added a comment -

Wayne's fixes have resolved the issue. I can no longer reproduce the problem.

Thanks for the quick turn around.

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Chuck Remes added a comment - Wayne's fixes have resolved the issue. I can no longer reproduce the problem. Thanks for the quick turn around.

People

  • Assignee:
    Unassigned
    Reporter:
    Chuck Remes
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    Updated:
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