Emmanuel Lecharny wrote: > "이희승 (Trustin Lee) <[EMAIL PROTECTED]>" wrote: >> Hi Emmanuel, >> > Hi again, >> You might be interested in the following question from Gaston Dombiak: >> >> http://markmail.org/message/uylaf2zauta6ppe7 >> >> And there's an answer there in my response made at 9 Apr 2008. >> > I don't think that your answer fits well in the scope of the question I > pushed. We don't want to throttle write on the server side, we just want > to send bytes as fast as possible, but be sure that those bytes are sent > and read by the client before sending some new (which will have to be > accumulated somewhere on the server until you get an OOM). > > This is really a critical issue for every server using MINA as a > malicious client could perfectly be use to kill the server just by > sending a request and never reading more than a few bytes of data, if I > interpret correctly what I have seen.
The client might be malicious or not because it can be simply slow without its will. Whatever kind of client is connected, the server should be responsible for slow connection. Again, there are two mechanisms: 1) Check scheduledWriteBytes before you write. If you are going to stream many messages, you might not want to write all of them immediately but want to write them chunk by chunk. Then you can check the scheduledWriteBytes in your WriteFuture listener or messageSent event handler. 2) There's writeTimeout property if a client is not reading even one message. > Peter Royal suggested to use a Callback to handle with such a problem, > and it sounds like a good idea (we have listeners we can use for that in > WriteFuture), but this has to be done in the ProtocolCodecFilter code, > which is a part of the MINA API. It's a good idea to privde a solution for preventing OOM due to fast write. Also, I think it's a must-have feature for all clients and servers. Therefore, what about adding the following two properties: * IoSessionConfig.scheduledWriteBytesThreshold * IoSessionConfig.scheduledWriteMessagesThreshold and making MINA to raise an exception when scheduledWrite(Bytes|Messages) becomes too large. Then your IoHandler will be notified with an exceptionCaught event. WDYT? -- Trustin Lee - Principal Software Engineer, JBoss, Red Hat -- what we call human nature is actually human habit -- http://gleamynode.net/
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