/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package co.cask.tephra.persist;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.server.namenode.LeaseExpiredException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.lang.reflect.Method;
/**
* Utility for handling HDFS file lease recovery. This is a copy-n-paste fork of
* {@link org.apache.hadoop.hbase.util.FSHDFSUtils} from the latest HBase 0.94 version (as of 0.94.12),
* which contains some additional fixes not present in our current HBase dependency version --
* mainly checking the return value of the {@code DistributedFileSystem.recoverLease()} call to verify that
* recovery succeeded.
*/
public class HDFSUtil {
private static final Logger LOG = LoggerFactory.getLogger(HDFSUtil.class);
/**
* Recover the lease from HDFS, retrying multiple times.
*/
public void recoverFileLease(final FileSystem fs, final Path p,
Configuration conf)
throws IOException {
// lease recovery not needed for local file system case.
if (!(fs instanceof DistributedFileSystem)) {
return;
}
recoverDFSFileLease((DistributedFileSystem) fs, p, conf);
}
/*
* Run the dfs recover lease. recoverLease is asynchronous. It returns:
* -false when it starts the lease recovery (i.e. lease recovery not *yet* done)
* - true when the lease recovery has succeeded or the file is closed.
* But, we have to be careful. Each time we call recoverLease, it starts the recover lease
* process over from the beginning. We could put ourselves in a situation where we are
* doing nothing but starting a recovery, interrupting it to start again, and so on.
* The findings over in HBASE-8354 have it that the namenode will try to recover the lease
* on the file's primary node. If all is well, it should return near immediately. But,
* as is common, it is the very primary node that has crashed and so the namenode will be
* stuck waiting on a socket timeout before it will ask another datanode to start the
* recovery. It does not help if we call recoverLease in the meantime and in particular,
* subsequent to the socket timeout, a recoverLease invocation will cause us to start
* over from square one (possibly waiting on socket timeout against primary node). So,
* in the below, we do the following:
* 1. Call recoverLease.
* 2. If it returns true, break.
* 3. If it returns false, wait a few seconds and then call it again.
* 4. If it returns true, break.
* 5. If it returns false, wait for what we think the datanode socket timeout is
* (configurable) and then try again.
* 6. If it returns true, break.
* 7. If it returns false, repeat starting at step 5. above.
*
* If HDFS-4525 is available, call it every second and we might be able to exit early.
*/
boolean recoverDFSFileLease(final DistributedFileSystem dfs, final Path p,
final Configuration conf)
throws IOException {
LOG.info("Recovering lease on dfs file " + p);
long startWaiting = System.currentTimeMillis();
// Default is 15 minutes. It's huge, but the idea is that if we have a major issue, HDFS
// usually needs 10 minutes before marking the nodes as dead. So we're putting ourselves
// beyond that limit 'to be safe'.
long recoveryTimeout = conf.getInt("hbase.lease.recovery.timeout", 900000) + startWaiting;
// This setting should be what the cluster dfs heartbeat is set to.
long firstPause = conf.getInt("hbase.lease.recovery.first.pause", 3000);
// This should be set to how long it'll take for us to timeout against primary datanode if it
// is dead. We set it to 61 seconds, 1 second than the default READ_TIMEOUT in HDFS, the
// default value for DFS_CLIENT_SOCKET_TIMEOUT_KEY.
long subsequentPause = conf.getInt("hbase.lease.recovery.dfs.timeout", 61 * 1000);
Method isFileClosedMeth = null;
// whether we need to look for isFileClosed method
boolean findIsFileClosedMeth = true;
boolean recovered = false;
// We break the loop if we succeed the lease recovery, timeout, or we throw an exception.
for (int nbAttempt = 0; !recovered; nbAttempt++) {
recovered = recoverLease(dfs, nbAttempt, p, startWaiting);
if (recovered || checkIfTimedout(conf, recoveryTimeout, nbAttempt, p, startWaiting)) {
break;
}
try {
// On the first time through wait the short 'firstPause'.
if (nbAttempt == 0) {
Thread.sleep(firstPause);
} else {
// Cycle here until subsequentPause elapses. While spinning, check isFileClosed if
// available (should be in hadoop 2.0.5... not in hadoop 1 though.
long localStartWaiting = System.currentTimeMillis();
while ((System.currentTimeMillis() - localStartWaiting) <
subsequentPause) {
Thread.sleep(conf.getInt("hbase.lease.recovery.pause", 1000));
if (findIsFileClosedMeth) {
try {
isFileClosedMeth = dfs.getClass().getMethod("isFileClosed",
new Class[]{ Path.class });
} catch (NoSuchMethodException nsme) {
LOG.debug("isFileClosed not available");
} finally {
findIsFileClosedMeth = false;
}
}
if (isFileClosedMeth != null && isFileClosed(dfs, isFileClosedMeth, p)) {
recovered = true;
break;
}
}
}
} catch (InterruptedException ie) {
InterruptedIOException iioe = new InterruptedIOException();
iioe.initCause(ie);
throw iioe;
}
}
return recovered;
}
boolean checkIfTimedout(final Configuration conf, final long recoveryTimeout,
final int nbAttempt, final Path p, final long startWaiting) {
if (recoveryTimeout < System.currentTimeMillis()) {
LOG.warn("Cannot recoverLease after trying for " +
conf.getInt("hbase.lease.recovery.timeout", 900000) +
"ms (hbase.lease.recovery.timeout); continuing, but may be DATALOSS!!!; " +
getLogMessageDetail(nbAttempt, p, startWaiting));
return true;
}
return false;
}
/**
* Try to recover the lease.
* @param dfs The filesystem instance.
* @param nbAttempt Count number of this attempt.
* @param p Path of the file to recover.
* @param startWaiting Timestamp of when we started attempting to recover the file lease.
* @return True if dfs#recoverLease came by true.
* @throws java.io.FileNotFoundException
*/
boolean recoverLease(final DistributedFileSystem dfs, final int nbAttempt, final Path p,
final long startWaiting)
throws FileNotFoundException {
boolean recovered = false;
try {
recovered = dfs.recoverLease(p);
LOG.info("recoverLease=" + recovered + ", " +
getLogMessageDetail(nbAttempt, p, startWaiting));
} catch (IOException e) {
if (e instanceof LeaseExpiredException && e.getMessage().contains("File does not exist")) {
// This exception comes out instead of FNFE, fix it
throw new FileNotFoundException("The given file wasn't found at " + p);
} else if (e instanceof FileNotFoundException) {
throw (FileNotFoundException) e;
}
LOG.warn(getLogMessageDetail(nbAttempt, p, startWaiting), e);
}
return recovered;
}
/**
* @param nbAttempt Attempt number for the lease recovery.
* @param p Path of the file to recover.
* @param startWaiting Timestamp of when we started attempting to recover the file lease.
* @return Detail to append to any log message around lease recovering.
*/
private String getLogMessageDetail(final int nbAttempt, final Path p, final long startWaiting) {
return "attempt=" + nbAttempt + " on file=" + p + " after " +
(System.currentTimeMillis() - startWaiting) + "ms";
}
/**
* Call HDFS-4525 isFileClosed if it is available.
* @param dfs Filesystem instance to use.
* @param m Method instance to call.
* @param p Path of the file to check is closed.
* @return True if file is closed.
*/
private boolean isFileClosed(final DistributedFileSystem dfs, final Method m, final Path p) {
try {
return (Boolean) m.invoke(dfs, p);
} catch (SecurityException e) {
LOG.warn("No access", e);
} catch (Exception e) {
LOG.warn("Failed invocation for " + p.toString(), e);
}
return false;
}
}