[GitHub] infodog opened a new issue #1544: ConcurrentModificationException with nonblocking logReader.readNext(true)

[GitBox <gi...@apache.org>]

infodog opened a new issue #1544: ConcurrentModificationException with nonblocking logReader.readNext(true) 
URL: https://github.com/apache/bookkeeper/issues/1544
 
 
   
   
   **BUG REPORT**
   
   1. Please describe the issue you observed:
   
   - What did you do?
   
   I do a nonblocking read from the server with three bookie.
   my code is 
   `reader = dlm.getInputStream(nextTxId);
                       while (true) {
                           try {
                               LogRecord record = reader.readNext(false);
                               if (record == null) {
                                   reader.close();
                                   reader = null;
                                   break;
                               }
                               if (record.getTransactionId() > getLocalLastTxId()) {
                                   LOG.info("updatelog " + this.nodeName + "," + this.instanceName + ":" + "newTransactionId:" + record.getTransactionId() + ",localLastTxId:" + getLocalLastTxId());
                                   updateLog(record);
                               }
                           } catch (LogEmptyException t) {
                               System.out.println("no record in log.");
                           } catch (Throwable ioe) {
                               // handle the exception
                               if(reader!=null){
                                   reader.close();
                               }
                               nextTxId = getLocalLastTxId();
                               reader = dlm.getInputStream(nextTxId);
                           }
   
                       }`
   
   and I observe an error log 
   
   `2018-07-15 23:05:01  [ DLM-/pigeon40namespace-OrderedScheduler-1-0:8345 ] - [ ERROR ]  Unexpected throwable caught  org.apache.bookkeeper.common.util.SafeRunnable.run(SafeRunnable.java:38)  
   java.util.ConcurrentModificationException
   	at java.util.HashMap$HashIterator.nextNode(HashMap.java:1437)
   	at java.util.HashMap$ValueIterator.next(HashMap.java:1466)
   	at org.apache.distributedlog.impl.ZKLogSegmentMetadataStore.lambda$notifyLogSegmentsUpdated$1(ZKLogSegmentMetadataStore.java:493)
   	at org.apache.bookkeeper.common.util.SafeRunnable.run(SafeRunnable.java:36)
   	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
   	at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
   	at java.util.concurrent.FutureTask.run(FutureTask.java)
   	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
   	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
   	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
   	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
   	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
   	at java.lang.Thread.run(Thread.java:745)`
   
   and then no more data is read.
   
   
   **BP**
   
   This is the master ticket for tracking BP-<bp-number> :
   
   [a short description for this BP]
   
   Proposal PR - #<pr-number>
   

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