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Intermittent NullPointerException under 9.1.1.0/9.1.2.0 #3999

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abiacco opened this issue Jul 7, 2016 · 19 comments
Closed

Intermittent NullPointerException under 9.1.1.0/9.1.2.0 #3999

abiacco opened this issue Jul 7, 2016 · 19 comments

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@abiacco
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abiacco commented Jul 7, 2016

I'm running my jruby app as a war under Tomcat 8.0.35.
Under 9.1.1.0 and 9.1.2.0 (i haven't seen the error on <= 9.1.0.0, yet) I will receive, upon war deployment:

LoadError: load error: ethon/curls/options -- java.lang.NullPointerException: null
require at org/jruby/RubyKernel.java:944
block in require at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274
load_dependency at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240
require at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274
at WEB-INF/vendor/bundle/gems/ethon-0.8.1/lib/ethon/curl.rb:2
require at org/jruby/RubyKernel.java:944

Now I thought this could be an ethon problem, but i've been using it a while and never saw this error (yet) up until trying 9.1.1.0/9.1.2.0.
In my testing to reproduce this, i am NOT hot deploying. I am stopping tomcat, removing the webapp dir, and starting tomcat every time.
@PetrKaleta mentioned that he was seeing this in issue #3680 under rake. I've only seen it once in rake upon building my webapp (out of a couple dozen builds), every other time it's on deployment.
It happens maybe once every 10 deployments.
Under suggestion from @enebo to enable ir.reading.debug I have posted my full log to:

https://gist.github.com/abiacco/897fb4829b1eb601670c09d9366c51f5

I do have a large log with ir.debug enabled as well. If requested, i prefer to provide that privately.

Thanks

-Tony

Environment

jruby 9.1.2.0 (2.3.0) 2016-05-26 7357c8f Java HotSpot(TM) 64-Bit Server VM 25.91-b14 on 1.8.0_91-b14 +jit [linux-x86_64]

CentOS release 6.7 (Final)
Tomcat 8.0.35
java server jre 8u91
warbler 2.0.3
bundler 1.12.5

Also tested on jruby 9.1.1.0 and java 8u77

Linux app-01.local 2.6.32-573.18.1.el6.x86_64 #1 SMP Tue Feb 9 22:46:17 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Expected Behavior

No NullPointerException and rack failure :)

Actual Behavior

Intermittent NullPointerException from ethon gem.

@abiacco
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abiacco commented Jul 11, 2016

After some testing on 9.1.0.0 I hit the error on 1 out of the 100 consecutive deploys i did.

@headius
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headius commented Jul 11, 2016

Intermittent usually means concurrency. I'll see if I can reproduce.

@headius
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headius commented Jul 11, 2016

Ok, the link you provided for ir.reading.debug output appears to be broken. Perhaps you can update that.

I'd be more interested in getting the following: reproduce with -d -Xbacktrace.style=full -Xjit.threshold=0 passed to JRuby, so we get the LoadError raw output and a full trace of all Ruby and JRuby code together.

Without a NullPointException trace (which -d should give you) I can only guess at this right now.

@abiacco
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abiacco commented Jul 11, 2016

@abiacco
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abiacco commented Jul 11, 2016

I'll try with the additional flags you requested. I can figure out their java/tomcat equivalents, except for -d. maybe -Djruby.debug.fullTrace=true?

@enebo enebo added this to the JRuby 9.1.3.0 milestone Jul 12, 2016
@enebo enebo added the ir label Jul 12, 2016
@enebo
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enebo commented Jul 12, 2016

So looking at that gist I can surmise when we prepare this code for compilation we do some data flow analysis (live variable). During that analysis we ask for the data for a particular BB and it returns null. This means something has a reference to and ID in our CFG which was never setup during our DFG construction (missed or dangling edge)

I think DataFlowGraph.buildFlowGraph will follow all nodes in the CFG. Unless we somehow have some errant incoming/outgoing edge referring to a node which no longer exists (which would be an invariant broken in CFG).

@abiacco we really really hope this is reproducible with -Xjit.threshold=0 (from Java end -Djruby.jit.threshold=0)

@abiacco
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abiacco commented Jul 12, 2016

I didn't really understand any of that but ok :)

Last night i ran a 100 deployment test and did not hit the error at all using:

-Djruby.jit.threshold=0 -Djruby.backtrace.style=full -Djruby.debug.fullTrace=true

I started the test again this morning without those 3 params and hit the error on deployment # 7

@abiacco
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abiacco commented Jul 19, 2016

Here's the gist with the extra trace flags

https://gist.github.com/abiacco/fc907d8afc57a56b3c11f17afc065680

@headius
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headius commented Aug 11, 2016

Can you still reproduce this with a master build (from http://ci.jruby.org)?

If so, I need you to pass -d to JRuby to force it to dump the underlying exception causing the LoadError in your traces. As it is I can't see what line the NPE actually happened at.

@abiacco
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abiacco commented Aug 12, 2016

I'll give it a go.

Regarding the -d, i still don't know how to pass this down through tomcat with a property.

@headius
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headius commented Aug 12, 2016

For Tomcat, set JVM property "jruby.cli.debug" to "true". That should be equivalent to passing -d.

@abiacco
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abiacco commented Aug 13, 2016

roger

@abiacco
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abiacco commented Aug 15, 2016

@headius whelp, 500 deployments with snapshot and I could not get the error to rear its head.

@headius
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headius commented Aug 15, 2016

@abiacco Ok. We're pushing to get 9.1.3.0 out so we'll call this fixed for now. If you can reproduce we'll reopen and look into it.

@headius headius closed this as completed Aug 15, 2016
@abiacco
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abiacco commented Aug 16, 2016

@headius Yep yep, that's fair. And i'll re-test once 9.1.3.0 is out obviously. Much appreciated

@JasonLunn
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@abiacco - I'm seeing this intermittently on JRuby 9.1.6.0

@PetrKaleta
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Same here, happening again in JRuby 9.1.6.0

@enebo
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enebo commented Nov 29, 2016

@JasonLunn @PetrKaleta can you supply your backtraces? I am trying to make sure this is the same NPE as in https://gist.github.com/abiacco/fc907d8afc57a56b3c11f17afc065680

@abiacco
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abiacco commented Nov 29, 2016

FYI, i haven't seen my NPE anymore, as of yet. i've been using 9.1.5.0 and just started with 9.1.6.0

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