Sahil Takiar created IMPALA-10139: ------------------------------------- Summary: Slow RPC logs can be misleading Key: IMPALA-10139 URL: https://issues.apache.org/jira/browse/IMPALA-10139 Project: IMPALA Issue Type: Improvement Reporter: Sahil Takiar
The slow RPC logs added in IMPALA-9128 are based on the total time taken to successfully complete a RPC. The issue is that there are many reasons why an RPC might take a long time to complete. An RPC is considered complete only when the receiver has processed that RPC. The problem is that due to client-driven back-pressure mechanism, it is entirely possible that the receiver RPC does not process a receiver RPC because {{KrpcDataStreamRecvr::SenderQueue::GetBatch}} just hasn't been called yet (indirectly called by {{ExchangeNode::GetNext}}). This can lead to flood of slow RPC logs, even though the RPCs might not actually be slow themselves. What is worse is that the because of the back-pressure mechanism, slowness from the client (e.g. Hue users) will propagate across all nodes involved in the query. -- This message was sent by Atlassian Jira (v8.3.4#803005)