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HDFS-12323. NameNode terminates after full GC thinking QJM unresponsive if full GC is much longer than timeout. Contributed by Erik Krogen.

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This commit is contained in:
Erik Krogen 2017-09-14 15:53:33 -07:00 committed by Konstantin V Shvachko
parent b9b607daa7
commit 90894c7262
2 changed files with 84 additions and 16 deletions
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69
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/QuorumCall.java
View File

@ -24,7 +24,7 @@
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.util.StopWatch;
import org.apache.hadoop.util.Time;
import org.apache.hadoop.util.Timer;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
@ -35,6 +35,7 @@
import com.google.protobuf.Message;
import com.google.protobuf.TextFormat;
/**
* Represents a set of calls for which a quorum of results is needed.
* @param <KEY> a key used to identify each of the outgoing calls
@ -60,11 +61,12 @@ class QuorumCall<KEY, RESULT> {
* fraction of the configured timeout for any call.
*/
private static final float WAIT_PROGRESS_WARN_THRESHOLD = 0.7f;
private final StopWatch quorumStopWatch = new StopWatch();
private final StopWatch quorumStopWatch;
private final Timer timer;
static <KEY, RESULT> QuorumCall<KEY, RESULT> create(
Map<KEY, ? extends ListenableFuture<RESULT>> calls) {
final QuorumCall<KEY, RESULT> qr = new QuorumCall<KEY, RESULT>();
Map<KEY, ? extends ListenableFuture<RESULT>> calls, Timer timer) {
final QuorumCall<KEY, RESULT> qr = new QuorumCall<KEY, RESULT>(timer);
for (final Entry<KEY, ? extends ListenableFuture<RESULT>> e : calls.entrySet()) {
Preconditions.checkArgument(e.getValue() != null,
"null future for key: " + e.getKey());
@ -82,18 +84,53 @@ public void onSuccess(RESULT res) {
}
return qr;
}
private QuorumCall() {
// Only instantiated from factory method above
static <KEY, RESULT> QuorumCall<KEY, RESULT> create(
Map<KEY, ? extends ListenableFuture<RESULT>> calls) {
return create(calls, new Timer());
}
/**
* Not intended for outside use.
*/
private QuorumCall() {
this(new Timer());
}
private QuorumCall(Timer timer) {
// Only instantiated from factory method above
this.timer = timer;
this.quorumStopWatch = new StopWatch(timer);
}
/**
* Used in conjunction with {@link #getQuorumTimeoutIncreaseMillis(long, int)}
* to check for pauses.
*/
private void restartQuorumStopWatch() {
quorumStopWatch.reset().start();
}
private boolean shouldIncreaseQuorumTimeout(long offset, int millis) {
/**
* Check for a pause (e.g. GC) since the last time
* {@link #restartQuorumStopWatch()} was called. If detected, return the
* length of the pause; else, -1.
* @param offset Offset the elapsed time by this amount; use if some amount
* of pause was expected
* @param millis Total length of timeout in milliseconds
* @return Length of pause, if detected, else -1
*/
private long getQuorumTimeoutIncreaseMillis(long offset, int millis) {
long elapsed = quorumStopWatch.now(TimeUnit.MILLISECONDS);
return elapsed + offset > (millis * WAIT_PROGRESS_INFO_THRESHOLD);
long pauseTime = elapsed + offset;
if (pauseTime > (millis * WAIT_PROGRESS_INFO_THRESHOLD)) {
QuorumJournalManager.LOG.info("Pause detected while waiting for " +
"QuorumCall response; increasing timeout threshold by pause time " +
"of " + pauseTime + " ms.");
return pauseTime;
} else {
return -1;
}
}
@ -119,7 +156,7 @@ public synchronized void waitFor(
int minResponses, int minSuccesses, int maxExceptions,
int millis, String operationName)
throws InterruptedException, TimeoutException {
long st = Time.monotonicNow();
long st = timer.monotonicNow();
long nextLogTime = st + (long)(millis * WAIT_PROGRESS_INFO_THRESHOLD);
long et = st + millis;
while (true) {
@ -128,7 +165,7 @@ public synchronized void waitFor(
if (minResponses > 0 && countResponses() >= minResponses) return;
if (minSuccesses > 0 && countSuccesses() >= minSuccesses) return;
if (maxExceptions >= 0 && countExceptions() > maxExceptions) return;
long now = Time.monotonicNow();
long now = timer.monotonicNow();
if (now > nextLogTime) {
long waited = now - st;
@ -154,8 +191,9 @@ public synchronized void waitFor(
long rem = et - now;
if (rem <= 0) {
// Increase timeout if a full GC occurred after restarting stopWatch
if (shouldIncreaseQuorumTimeout(0, millis)) {
et = et + millis;
long timeoutIncrease = getQuorumTimeoutIncreaseMillis(0, millis);
if (timeoutIncrease > 0) {
et += timeoutIncrease;
} else {
throw new TimeoutException();
}
@ -165,8 +203,9 @@ public synchronized void waitFor(
rem = Math.max(rem, 1);
wait(rem);
// Increase timeout if a full GC occurred after restarting stopWatch
if (shouldIncreaseQuorumTimeout(-rem, millis)) {
et = et + millis;
long timeoutIncrease = getQuorumTimeoutIncreaseMillis(-rem, millis);
if (timeoutIncrease > 0) {
et += timeoutIncrease;
}
}
}

31
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/client/TestQuorumCall.java
View File

@ -23,7 +23,7 @@
import java.util.TreeMap;
import java.util.concurrent.TimeoutException;
import org.apache.hadoop.hdfs.qjournal.client.QuorumCall;
import org.apache.hadoop.util.FakeTimer;
import org.junit.Test;
import com.google.common.base.Joiner;
@ -83,4 +83,33 @@ public void testQuorumFailsWithoutResponse() throws Exception {
}
}
@Test(timeout=10000)
public void testQuorumSucceedsWithLongPause() throws Exception {
final Map<String, SettableFuture<String>> futures = ImmutableMap.of(
"f1", SettableFuture.<String>create());
FakeTimer timer = new FakeTimer() {
private int callCount = 0;
@Override
public long monotonicNowNanos() {
callCount++;
if (callCount == 1) {
long old = super.monotonicNowNanos();
advance(1000000);
return old;
} else if (callCount == 10) {
futures.get("f1").set("first future");
return super.monotonicNowNanos();
} else {
return super.monotonicNowNanos();
}
}
};
QuorumCall<String, String> q = QuorumCall.create(futures, timer);
assertEquals(0, q.countResponses());
q.waitFor(1, 0, 0, 3000, "test"); // wait for 1 response
}
}