I will go for live lock as well. But yes, stack dumps lie. I think jstack
-F might be harsher and give a different result.

But that said, you still have a deadlock. As mentioned

"New I/O worker #1810850" waiting on 0x0000000080ac88f0 is held by "New I/O
worker #1810853" <-- waiting for one another
"New I/O worker #1810853" waiting on 0x00000000802ba7f8 is held by "New I/O
worker #1810850" <-- waiting for one another

My question would be: Why is kudu wanting to get so much SSLContexts? Can't
it reuse them? (I don't know the api well, so maybe it's normal)


On 11 October 2017 at 06:48, Kirk Pepperdine <[email protected]> wrote:

> My vote is for live lock.. but that would be conditional on seeing all the
> stack traces.
>
> — Kirk
>
> On Oct 11, 2017, at 12:07 PM, Todd Lipcon <[email protected]> wrote:
>
> On Wed, Oct 11, 2017 at 12:29 AM, Kirk Pepperdine <[email protected]>
> wrote:
>
>> Not at all off topic… first, thread dumps lie like a rug… and here is why…
>>
>> for each thread {
>>     safe point
>>     create stack trace for that thread
>>     release threads from safe point
>> }
>>
>> And while rugs may attempt to cover the debris that you’ve swept under
>> them, that debris leaves a clearly visible lump that suggests that you have
>> a congestion problem on locks in both sun.security.provider.Sun and
>> java.lang.Class…. What could possibly go wrong?
>>
>
> Interesting. I remember investigating this back in the Java 6 days and at
> that time 'jstack -l' caused a global safepoint before iterating over the
> threads, and then only resumed upon completion (implemented by
> VM_ThreadDump in vm_operations.cpp). It appears that in JDK 7 this was
> switched over to the behavior that you describe.
>
> Either way, I'm looking at about 10 stack traces taken over a period of 3
> minutes and they have 100% identical "java-level deadlock" output. So I
> suppose it's possible that they are live-locked on the same sets of locks
> in the exact same threads but seems fairly unlikely.
>
> As for the congestion problem, I did find this JDK bug the other day:
> https://bugs.openjdk.java.net/browse/JDK-8133070 which aims to reduce
> contention, but no mention of a deadlock. We'll probably ask the customer
> to bump to a newer JDK with this fix and see if it magically goes away.
>
> -Todd
>
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