[ https://issues.apache.org/jira/browse/HDFS-17590?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Elmer J Fudd updated HDFS-17590: -------------------------------- Description: While reading blocks of data using `DFSInputStream` in `createBlockReader`, a `IOException` originating from `getBlockAt()` that triggers a retry iteration results in a `NullPointerException` when passing `dnInfo` to `addToLocalDeadNodes` in the catch block. This is the relevant callstack portion from our logs (from 3.4.0, but we still experience this with versions going into 3.4.1 as recently as late June): {noformat} ... java.lang.NullPointerException at java.base/java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011) at java.base/ java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1006) at org.apache.hadoop.hdfs.DFSInputStream.addToLocalDeadNodes(DFSInputStream.java:184) at org.apache.hadoop.hdfs.DFSStripedInputStream.createBlockReader(DFSStripedInputStream.java:279) at org.apache.hadoop.hdfs.StripeReader.readChunk(StripeReader.java:304) at org.apache.hadoop.hdfs.StripeReader.readStripe(StripeReader.java:335) at org.apache.hadoop.hdfs.DFSStripedInputStream.fetchBlockByteRange(DFSStripedInputStream.java:504) at org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1472) at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1436) at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:124) at org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:119) ...{noformat} What we observe is that `getBlockAt()` thorws an `IOException` [here|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L478] {code:java} //check offset if (offset < 0 || offset >= getFileLength()) { throw new IOException("offset < 0 || offset >= getFileLength(), offset=" + offset + ", locatedBlocks=" + locatedBlocks); } {code} This is eventually caught in `createBlockReader`. The catch block attempts to handle the error and, as part of the error handling, invokes the `addToLocalDeadNodes` method. The `dnInfo` object passed to this method is actually `NULL` as it wasn't fully allocated ([here)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247], which results in a `NullPointerException`. To sum up, this is the failure path according to the logs: # `IOException` is thrown in `getBlockAt` ([code|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L479]) # The exception propagates to `getBlockGroupAt` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L476]) # It further propagates to `refreshLocatedBlock` ([code)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L459] # `IOException` caught in `createBlockReader` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247]) # Error handling in the catch block of `createBlockReader` invokes `addToLocalDeadNodes` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L281]) # Execution throws `NullPointerException` since `dnInfo` is NULL A simple fix as a `NULL` check before calling `addToLocalDeadNodes`, and similarly adjusting the log messages in the `catch` block where `dnInfo` is dereferenced, should solve the issue. was: While reading blocks of data using `DFSInputStream` in `createBlockReader`, a `IOException` originating from `getBlockAt()` that triggers a retry iteration results in a `NullPointerException` when passing `dnInfo` to `addToLocalDeadNodes` in the catch block. This is the relevant callstack portion from our logs (from 3.4.0, but we still experience this with versions going into 3.4.1 as recently as late June): {noformat} ... java.lang.NullPointerException at java.base/java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011) at java.base/ java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1006) at org.apache.hadoop.hdfs.DFSInputStream.addToLocalDeadNodes(DFSInputStream.java:184) at org.apache.hadoop.hdfs.DFSStripedInputStream.createBlockReader(DFSStripedInputStream.java:279) at org.apache.hadoop.hdfs.StripeReader.readChunk(StripeReader.java:304) at org.apache.hadoop.hdfs.StripeReader.readStripe(StripeReader.java:335) at org.apache.hadoop.hdfs.DFSStripedInputStream.fetchBlockByteRange(DFSStripedInputStream.java:504) at org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1472) at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1436) at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:124) at org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:119) ...{noformat} What we observe is that `getBlockAt()` thorws an `IOException` [here|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L478] {code:java} //check offset if (offset < 0 || offset >= getFileLength()) { throw new IOException("offset < 0 || offset >= getFileLength(), offset=" + offset + ", locatedBlocks=" + locatedBlocks); } {code} This is eventually caught in `createBlockReader`. The catch block attempts to handle the error and, as part of the error handling, invokes the `addToLocalDeadNodes` method. The `dnInfo` object passed to this method is actually `NULL` as it wasn't fully allocated ([here)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247], which results in a `NullPointerException`. To sum up, this is the failure path according to the logs: # `IOException` is thrown in `getBlockAt` ([code|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L479]) # The exception propagates to `getBlockGroupAt` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L476]) # It further propagates to `refreshLocatedBlock` ([code)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L459] # `IOException` caught in `createBlockReader` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247]) # Error handling in the catch block of `createBlockReader` invokes `addToLocalDeadNodes` ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L281]) # Execution throws `NullPointerException` since `dnInfo` is NULL A simple fix as a `NULL` check before calling `addToLocalDeadNodes`, and similarly adjusting the log messages in the `catch` block, should solve the issue. > `NullPointerException` triggered in `createBlockReader` during retry iteration > ------------------------------------------------------------------------------ > > Key: HDFS-17590 > URL: https://issues.apache.org/jira/browse/HDFS-17590 > Project: Hadoop HDFS > Issue Type: Bug > Affects Versions: 3.4.0 > Reporter: Elmer J Fudd > Priority: Critical > > While reading blocks of data using `DFSInputStream` in `createBlockReader`, a > `IOException` originating from `getBlockAt()` that triggers a retry iteration > results in a `NullPointerException` when passing `dnInfo` to > `addToLocalDeadNodes` in the catch block. > This is the relevant callstack portion from our logs (from 3.4.0, but we > still experience this with versions going into 3.4.1 as recently as late > June): > {noformat} > ... > java.lang.NullPointerException > at > java.base/java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011) > > at java.base/ > java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1006) > at > org.apache.hadoop.hdfs.DFSInputStream.addToLocalDeadNodes(DFSInputStream.java:184) > > at > org.apache.hadoop.hdfs.DFSStripedInputStream.createBlockReader(DFSStripedInputStream.java:279) > > at org.apache.hadoop.hdfs.StripeReader.readChunk(StripeReader.java:304) > at org.apache.hadoop.hdfs.StripeReader.readStripe(StripeReader.java:335) > at > org.apache.hadoop.hdfs.DFSStripedInputStream.fetchBlockByteRange(DFSStripedInputStream.java:504) > > at org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1472) > at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1436) > at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:124) > at > org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:119) > ...{noformat} > What we observe is that `getBlockAt()` thorws an `IOException` > [here|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L478] > {code:java} > //check offset > if (offset < 0 || offset >= getFileLength()) { > throw new IOException("offset < 0 || offset >= getFileLength(), offset=" > + offset > + ", locatedBlocks=" + locatedBlocks); > } > {code} > This is eventually caught in `createBlockReader`. The catch block attempts to > handle the error and, as part of the error handling, invokes the > `addToLocalDeadNodes` method. The `dnInfo` object passed to this method is > actually `NULL` as it wasn't fully allocated > ([here)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247], > which results in a `NullPointerException`. > To sum up, this is the failure path according to the logs: > # `IOException` is thrown in `getBlockAt` > ([code|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L479]) > # The exception propagates to `getBlockGroupAt` > ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L476]) > # It further propagates to `refreshLocatedBlock` > ([code)|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L459] > # `IOException` caught in `createBlockReader` > ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L247]) > # Error handling in the catch block of `createBlockReader` invokes > `addToLocalDeadNodes` > ([code|https://github.com/apache/hadoop/blob/4525c7e35ea22d7a6350b8af10eb8d2ff68376e7/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java#L281]) > # Execution throws `NullPointerException` since `dnInfo` is NULL > A simple fix as a `NULL` check before calling `addToLocalDeadNodes`, and > similarly adjusting the log messages in the `catch` block where `dnInfo` is > dereferenced, should solve the 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