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Posted to dev@storm.apache.org by "Sean Zhong (JIRA)" <ji...@apache.org> on 2014/06/09 16:02:01 UTC
[jira] [Updated] (STORM-342) Contention in Disruptor Queue which
may cause message out of order
[ https://issues.apache.org/jira/browse/STORM-342?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sean Zhong updated STORM-342:
-----------------------------
Description:
Disruptor contains a potential contention bug between consumer and producer:
```java
class Disruptor {
...
public void publish(Object obj, boolean block) throws InsufficientCapacityException {
if(consumerStartedFlag) {
final long id;
if(block) {
id = _buffer.next();
} else {
id = _buffer.tryNext(1);
}
final MutableObject m = _buffer.get(id);
m.setObject(obj);
_buffer.publish(id);
} else {
_cache.add(obj);
if(consumerStartedFlag) flushCache();
}
}
public void consumerStarted() {
if(!consumerStartedFlag) {
consumerStartedFlag = true;
flushCache();
}
}
}
```
Suppose the following sequence to reproduce this bug:
1. consumer not started.
2. producer in another thread publish message "1", as "consumerStartedFlag" == false, it will publish it into cache.
3. consumerStarted() is called. consumerStartedFlag is set to true, but flushCache() is not called yet.
4. producer in another thread publish message "2", as "consumerStartedFlag" == true now, it will publish directly in RingBuffer.
5. flushCache() is called in consumerStarted()
6. FLUSH_CACHE object is published RingBuffer, it will mark the position of message "1" in RingBuffer.
7. consume() is called, it will first fecth "2", then "1"
8. message order is wrong!
I found this after troubleshooting a tricky random failure(1 in 100 times). It usually happen when producer and consumer colocated in same process, for example, the task send queue thread as producer, produce message to local task receive queue in same worker.
was:
Disruptor contains a potential contention bug between consumer and producer:
class Disruptor {
...
public void publish(Object obj, boolean block) throws InsufficientCapacityException {
if(consumerStartedFlag) {
final long id;
if(block) {
id = _buffer.next();
} else {
id = _buffer.tryNext(1);
}
final MutableObject m = _buffer.get(id);
m.setObject(obj);
_buffer.publish(id);
} else {
_cache.add(obj);
if(consumerStartedFlag) flushCache();
}
}
public void consumerStarted() {
if(!consumerStartedFlag) {
consumerStartedFlag = true;
flushCache();
}
}
}
Suppose the following sequence to reproduce this bug:
1. consumer not started.
2. producer in another thread publish message "1", as "consumerStartedFlag" == false, it will publish it into cache.
3. consumerStarted() is called. consumerStartedFlag is set to true, but flushCache() is not called yet.
4. producer in another thread publish message "2", as "consumerStartedFlag" == true now, it will publish directly in RingBuffer.
5. flushCache() is called in consumerStarted()
6. FLUSH_CACHE object is published RingBuffer, it will mark the position of message "1" in RingBuffer.
7. consume() is called, it will first fecth "2", then "1"
8. message order is wrong!
I found this after troubleshooting a tricky random failure(1 in 100 times). It usually happen when producer and consumer colocated in same process, for example, the task send queue thread as producer, produce message to local task receive queue in same worker.
> Contention in Disruptor Queue which may cause message out of order
> ------------------------------------------------------------------
>
> Key: STORM-342
> URL: https://issues.apache.org/jira/browse/STORM-342
> Project: Apache Storm (Incubating)
> Issue Type: Bug
> Reporter: Sean Zhong
> Priority: Critical
>
> Disruptor contains a potential contention bug between consumer and producer:
> ```java
> class Disruptor {
> ...
> public void publish(Object obj, boolean block) throws InsufficientCapacityException {
> if(consumerStartedFlag) {
> final long id;
> if(block) {
> id = _buffer.next();
> } else {
> id = _buffer.tryNext(1);
> }
> final MutableObject m = _buffer.get(id);
> m.setObject(obj);
> _buffer.publish(id);
> } else {
> _cache.add(obj);
> if(consumerStartedFlag) flushCache();
> }
> }
>
> public void consumerStarted() {
> if(!consumerStartedFlag) {
> consumerStartedFlag = true;
> flushCache();
> }
> }
> }
> ```
> Suppose the following sequence to reproduce this bug:
> 1. consumer not started.
> 2. producer in another thread publish message "1", as "consumerStartedFlag" == false, it will publish it into cache.
> 3. consumerStarted() is called. consumerStartedFlag is set to true, but flushCache() is not called yet.
> 4. producer in another thread publish message "2", as "consumerStartedFlag" == true now, it will publish directly in RingBuffer.
> 5. flushCache() is called in consumerStarted()
> 6. FLUSH_CACHE object is published RingBuffer, it will mark the position of message "1" in RingBuffer.
> 7. consume() is called, it will first fecth "2", then "1"
> 8. message order is wrong!
> I found this after troubleshooting a tricky random failure(1 in 100 times). It usually happen when producer and consumer colocated in same process, for example, the task send queue thread as producer, produce message to local task receive queue in same worker.
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