[tor-bugs] #20440 [Metrics/metrics-lib]: endless wait in BlockingIteratorImpl

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#20440: endless wait in BlockingIteratorImpl
-------------------------------------+---------------------
     Reporter:  iwakeh               |      Owner:  karsten
         Type:  defect               |     Status:  new
     Priority:  High                 |  Milestone:
    Component:  Metrics/metrics-lib  |    Version:
     Severity:  Normal               |   Keywords:
Actual Points:                       |  Parent ID:
       Points:                       |   Reviewer:
      Sponsor:                       |
-------------------------------------+---------------------
 As reported by David:

 Onionoo updater didn't stop after supposedly successful run.

 Here's the relevant thread dump part:

 {{{
 "Thread-0" #8 prio=5 os_prio=0 tid=0x00007f0d602f4000 nid=0x21a7 in
 Object.wait() [0x00007f0d435e0000]
    java.lang.Thread.State: WAITING (on object monitor)
         at java.lang.Object.wait(Native Method)
         - waiting on <0x00000007157e4ee0> (a
 org.torproject.descriptor.impl.BlockingIteratorImpl)
         at java.lang.Object.wait(Object.java:502)
         at
 org.torproject.descriptor.impl.BlockingIteratorImpl.add(BlockingIteratorImpl.java:40)
         - locked <0x00000007157e4ee0> (a
 org.torproject.descriptor.impl.BlockingIteratorImpl)
         at
 org.torproject.descriptor.impl.DescriptorReaderImpl$DescriptorReaderRunnable.readDescriptors(DescriptorReaderImpl.java:291)
         at
 org.torproject.descriptor.impl.DescriptorReaderImpl$DescriptorReaderRunnable.run(DescriptorReaderImpl.java:188)
         at java.lang.Thread.run(Thread.java:745)

 }}}

 This is the while loop in BlockingIteratorImpl.add
 {{{
     while (this.queue.size() >= this.maxQueueSize) {
       try {
         wait();
       } catch (InterruptedException e) {
         /* nothing to be done */
       }
     }
 }}}

 As there are no consumers anymore and the queue is full the while-loop
 doesn't stop.

--
Ticket URL: <https://troodi.torproject.org/projects/tor/ticket/20440>
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