hddong commented on code in PR #2687:
URL: https://github.com/apache/incubator-kyuubi/pull/2687#discussion_r876668226
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kyuubi-ha/src/main/scala/org/apache/kyuubi/ha/client/zookeeper/ZookeeperDiscoveryClient.scala:
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@@ -143,9 +143,34 @@ class ZookeeperDiscoveryClient(conf: KyuubiConf) extends
DiscoveryClient {
try {
lock = new InterProcessSemaphoreMutex(zkClient, lockPath)
// Acquire a lease. If no leases are available, this method blocks
until either the
- // maximum number of leases is increased or another client/process
closes a lease
- lock.acquire(timeout, unit)
+ // maximum number of leases is increased or another client/process
closes a lease.
+ //
+ // Here, we should throw exception if timeout during acquiring lock.
+ // Let's say we have three clients with same request lock to two
kyuubi server instances.
+ //
+ // client A ---> kyuubi X -- first acquired \
+ // client B ---> kyuubi X -- second acquired -- zookeeper
+ // client C ---> kyuubi Y -- third acquired /
+ //
+ // The first client A acqiured the lock then B and C are blocked until
A release the lock,
+ // with the A created engine state:
+ // - SUCCESS
+ // B acquired the lock then get engine ref and release the lock.
+ // C acquired the lock then get engine ref and release the lock.
+ // - FAILED or TIMEOUT
+ // B acquired the lock then try to create engine again if not
timeout.
+ // C should be timeout and throw exception back to client. This
fast fail
+ // to avoid client too long to waiting in concurrent.
+
+ // Return false means we are timeout
+ val acquired = lock.acquire(timeout, unit)
Review Comment:
It's OK to
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