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Patrick Hunt commented on ZOOKEEPER-900: ---------------------------------------- I see some great information about how the code/algos operate being detailed in these jiras. I highly encourage you guys to document this stuff in either the code or in a separate document available on the wiki/forrest (now mvn site, whatever). It's critical that we provide more details like this to our devs. See ZOOKEEPER-918 as a great example of what I'm talking about. (although adding more comments to the code is fine too). Basically, if you find yourself describing something in a jira that's not documented already, consider documenting it. Thanks. > FLE implementation should be improved to use non-blocking sockets > ----------------------------------------------------------------- > > Key: ZOOKEEPER-900 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-900 > Project: Zookeeper > Issue Type: Bug > Reporter: Vishal K > Assignee: Vishal K > Priority: Critical > Fix For: 3.4.0 > > Attachments: ZOOKEEPER-900.patch, ZOOKEEPER-900.patch1, > ZOOKEEPER-900.patch2 > > > From earlier email exchanges: > 1. Blocking connects and accepts: > a) The first problem is in manager.toSend(). This invokes connectOne(), which > does a blocking connect. While testing, I changed the code so that > connectOne() starts a new thread called AsyncConnct(). AsyncConnect.run() > does a socketChannel.connect(). After starting AsyncConnect, connectOne > starts a timer. connectOne continues with normal operations if the connection > is established before the timer expires, otherwise, when the timer expires it > interrupts AsyncConnect() thread and returns. In this way, I can have an > upper bound on the amount of time we need to wait for connect to succeed. Of > course, this was a quick fix for my testing. Ideally, we should use Selector > to do non-blocking connects/accepts. I am planning to do that later once we > at least have a quick fix for the problem and consensus from others for the > real fix (this problem is big blocker for us). Note that it is OK to do > blocking IO in SenderWorker and RecvWorker threads since they block IO to the > respective ! peer. > b) The blocking IO problem is not just restricted to connectOne(), but also > in receiveConnection(). The Listener thread calls receiveConnection() for > each incoming connection request. receiveConnection does blocking IO to get > peer's info (s.read(msgBuffer)). Worse, it invokes connectOne() back to the > peer that had sent the connection request. All of this is happening from the > Listener. In short, if a peer fails after initiating a connection, the > Listener thread won't be able to accept connections from other peers, because > it would be stuck in read() or connetOne(). Also the code has an inherent > cycle. initiateConnection() and receiveConnection() will have to be very > carefully synchronized otherwise, we could run into deadlocks. This code is > going to be difficult to maintain/modify. > Also see: https://issues.apache.org/jira/browse/ZOOKEEPER-822 -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.