[HDFS-11887] Shared XceiverClient should be closed if there is no open clients to avoid resource leak

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: HDFS-7240
• Component/s: ozone
• Hadoop Flags: Reviewed
• Assignee: Mukul Kumar Singh
• Reporter: Mukul Kumar Singh
• Created: 26/May/17 02:46
• Updated: 26/Apr/18 21:51
• Resolved: 06/Jun/17 13:21

Description

XceiverClientManager doesn't close client on eviction which can leak resources.

public XceiverClientManager(Configuration conf) {
.
.
.
            public void onRemoval(
                RemovalNotification<String, XceiverClientWithAccessInfo>
                  removalNotification) {
              // If the reference count is not 0, this xceiver client should not
              // be evicted, add it back to the cache.
              WithAccessInfo info = removalNotification.getValue();
              if (info.hasRefence()) {
                synchronized (XceiverClientManager.this.openClient) {
                  XceiverClientManager.this
                      .openClient.put(removalNotification.getKey(), info);
                }
              }

Also a stack overflow can be triggered because of putting the element back in the cache on eviction.

                synchronized (XceiverClientManager.this.openClient) {
                  XceiverClientManager.this
                      .openClient.put(removalNotification.getKey(), info);
                }

This bug will try to fix both of these cases.