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ASF GitHub Bot updated HDFS-15413: ---------------------------------- Labels: pull-request-available (was: ) > DFSStripedInputStream throws exception when datanodes close idle connections > ---------------------------------------------------------------------------- > > Key: HDFS-15413 > URL: https://issues.apache.org/jira/browse/HDFS-15413 > Project: Hadoop HDFS > Issue Type: Bug > Components: ec, erasure-coding, hdfs-client > Affects Versions: 3.1.3 > Environment: - Hadoop 3.1.3 > - erasure coding with ISA-L and RS-3-2-1024k scheme > - running in kubernetes > - dfs.client.socket-timeout = 10000 > - dfs.datanode.socket.write.timeout = 10000 > Reporter: Andrey Elenskiy > Priority: Critical > Labels: pull-request-available > Attachments: out.log > > > We've run into an issue with compactions failing in HBase when erasure coding > is enabled on a table directory. After digging further I was able to narrow > it down to a seek + read logic and able to reproduce the issue with hdfs > client only: > {code:java} > import org.apache.hadoop.conf.Configuration; > import org.apache.hadoop.fs.Path; > import org.apache.hadoop.fs.FileSystem; > import org.apache.hadoop.fs.FSDataInputStream; > public class ReaderRaw { > public static void main(final String[] args) throws Exception { > Path p = new Path(args[0]); > int bufLen = Integer.parseInt(args[1]); > int sleepDuration = Integer.parseInt(args[2]); > int countBeforeSleep = Integer.parseInt(args[3]); > int countAfterSleep = Integer.parseInt(args[4]); > Configuration conf = new Configuration(); > FSDataInputStream istream = FileSystem.get(conf).open(p); > byte[] buf = new byte[bufLen]; > int readTotal = 0; > int count = 0; > try { > while (true) { > istream.seek(readTotal); > int bytesRemaining = bufLen; > int bufOffset = 0; > while (bytesRemaining > 0) { > int nread = istream.read(buf, 0, bufLen); > if (nread < 0) { > throw new Exception("nread is less than zero"); > } > readTotal += nread; > bufOffset += nread; > bytesRemaining -= nread; > } > count++; > if (count == countBeforeSleep) { > System.out.println("sleeping for " + sleepDuration + " > milliseconds"); > Thread.sleep(sleepDuration); > System.out.println("resuming"); > } > if (count == countBeforeSleep + countAfterSleep) { > System.out.println("done"); > break; > } > } > } catch (Exception e) { > System.out.println("exception on read " + count + " read total " > + readTotal); > throw e; > } > } > } > {code} > The issue appears to be due to the fact that datanodes close the connection > of EC client if it doesn't fetch next packet for longer than > dfs.client.socket-timeout. The EC client doesn't retry and instead assumes > that those datanodes went away resulting in "missing blocks" exception. > I was able to consistently reproduce with the following arguments: > {noformat} > bufLen = 1000000 (just below 1MB which is the size of the stripe) > sleepDuration = (dfs.client.socket-timeout + 1) * 1000 (in our case 11000) > countBeforeSleep = 1 > countAfterSleep = 7 > {noformat} > I've attached the entire log output of running the snippet above against > erasure coded file with RS-3-2-1024k policy. And here are the logs from > datanodes of disconnecting the client: > datanode 1: > {noformat} > 2020-06-15 19:06:20,697 INFO datanode.DataNode: Likely the client has stopped > reading, disconnecting it (datanode-v11-0-hadoop.hadoop:9866:DataXceiver > error processing READ_BLOCK operation src: /10.128.23.40:53748 dst: > /10.128.14.46:9866); java.net.SocketTimeoutException: 10000 millis timeout > while waiting for channel to be ready for write. ch : > java.nio.channels.SocketChannel[connected local=/10.128.14.46:9866 > remote=/10.128.23.40:53748] > {noformat} > datanode 2: > {noformat} > 2020-06-15 19:06:20,341 INFO datanode.DataNode: Likely the client has stopped > reading, disconnecting it (datanode-v11-1-hadoop.hadoop:9866:DataXceiver > error processing READ_BLOCK operation src: /10.128.23.40:48772 dst: > /10.128.9.42:9866); java.net.SocketTimeoutException: 10000 millis timeout > while waiting for channel to be ready for write. ch : > java.nio.channels.SocketChannel[connected local=/10.128.9.42:9866 > remote=/10.128.23.40:48772] > {noformat} > datanode 3: > {noformat} > 2020-06-15 19:06:20,467 INFO datanode.DataNode: Likely the client has stopped > reading, disconnecting it (datanode-v11-3-hadoop.hadoop:9866:DataXceiver > error processing READ_BLOCK operation src: /10.128.23.40:57184 dst: > /10.128.16.13:9866); java.net.SocketTimeoutException: 10000 millis timeout > while waiting for channel to be ready for write. ch : > java.nio.channels.SocketChannel[connected local=/10.128.16.13:9866 > remote=/10.128.23.40:57184] > {noformat} > I've tried running the same code again non-ec files with replication of 3 and > was not able to reproduce the issue with any parameters. Looking through the > code, it's pretty clear that non-ec DFSInputStream retries reads after > exception: > https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L844 > Let me know if you need any more information that can help you out with > addressing this issue. -- This message was sent by Atlassian Jira (v8.20.10#820010) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org