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From "Emmanuel Lecharny (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DIRMINA-764) DDOS possible in only a few seconds...
Date Tue, 16 Feb 2010 18:09:28 GMT

    [ https://issues.apache.org/jira/browse/DIRMINA-764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12834351#action_12834351
] 

Emmanuel Lecharny commented on DIRMINA-764:
-------------------------------------------

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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