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https://issues.apache.org/jira/browse/DIRMINA-764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12834351#action_12834351
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Emmanuel Lecharny commented on DIRMINA-764:
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As I suspected, the way MINA handle writes to the client is buggy.
Messages stored in the WriteQueue waiting to be sent are processed one by one,
with a loop done on the select() process between each of them. The queue will
be emptied very slowly if clients never stop injecting new messages
asynchronously...
It has to be understood that for every message to be written, an empty message
is added in the queue to be able to generate a messageSent event. Not optimal
...
> DDOS possible in only a few seconds...
> --------------------------------------
>
> Key: DIRMINA-764
> URL: https://issues.apache.org/jira/browse/DIRMINA-764
> Project: MINA
> Issue Type: Bug
> Affects Versions: 2.0.0-RC1
> Reporter: Emmanuel Lecharny
> Priority: Blocker
> Fix For: 2.0.0
>
> Attachments: screenshot-1.jpg, screenshot-2.jpg
>
>
> We can kill a server in just a few seconds using the stress test found in
> DIRMINA-762.
> If we inject messages with no delay, using 50 threads to do that, the
> ProtocolCodecFilter$MessageWriteRequest is stuffed with hundred of thousands
> messages waiting to be written back to the client, with no success.
> On the client side, we receive almost no messages :
> 0 messages/sec (total messages received 1)
> 2 messages/sec (total messages received 11)
> 8 messages/sec (total messages received 55)
> 8 messages/sec (total messages received 95)
> 9 messages/sec (total messages received 144)
> 3 messages/sec (total messages received 162)
> 1 messages/sec (total messages received 169)
> ...
> On the server side, the memory is totally swamped in 20 seconds, with no way
> to recover :
> Exception in thread "pool-1-thread-1" java.lang.OutOfMemoryError: Java heap
> space
> (see graph attached)
> On the server, ConcurrentLinkedQueue contain the messages to be written (in
> my case, 724 499 Node are present). There are also 361629
> DefaultWriteRequests, 361628 DefaultWriteFutures, 361625 SimpleBuffer, 361
> 618 ProtocolCodecFilter$MessageWriteRequest and 361 614
> ProtocolCodecFilter$EncodedWriteRequests.
> That mean we don't flush them to the client at all.
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