From 2c769167dbdb66c52d2ba7b7193a686444085570 Mon Sep 17 00:00:00 2001 From: Akira Ajisaka Date: Tue, 20 Jun 2017 16:35:54 +0900 Subject: [PATCH] HDFS-11345. Document the configuration key for FSNamesystem lock fairness. Contributed by Erik Krogen. --- .../java/org/apache/hadoop/hdfs/DFSConfigKeys.java | 4 ++++ .../hadoop/hdfs/server/namenode/FSNamesystemLock.java | 5 ++++- .../hadoop-hdfs/src/main/resources/hdfs-default.xml | 10 ++++++++++ .../hdfs/server/namenode/TestFSNamesystemLock.java | 7 ++++--- 4 files changed, 22 insertions(+), 4 deletions(-) diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java index eaaff6071d..e7aba4ee62 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java +++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java @@ -423,6 +423,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys { public static final long DFS_NAMENODE_MAX_LOCK_HOLD_TO_RELEASE_LEASE_MS_DEFAULT = 25; + public static final String DFS_NAMENODE_FSLOCK_FAIR_KEY = + "dfs.namenode.fslock.fair"; + public static final boolean DFS_NAMENODE_FSLOCK_FAIR_DEFAULT = true; + public static final String DFS_NAMENODE_LOCK_DETAILED_METRICS_KEY = "dfs.namenode.lock.detailed-metrics.enabled"; public static final boolean DFS_NAMENODE_LOCK_DETAILED_METRICS_DEFAULT = diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystemLock.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystemLock.java index be33c4b532..8c60faac3f 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystemLock.java +++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystemLock.java @@ -32,6 +32,8 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_LOCK_SUPPRESS_WARNING_INTERVAL_DEFAULT; import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_LOCK_SUPPRESS_WARNING_INTERVAL_KEY; +import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_FSLOCK_FAIR_DEFAULT; +import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_FSLOCK_FAIR_KEY; import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LOCK_DETAILED_METRICS_DEFAULT; import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LOCK_DETAILED_METRICS_KEY; import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_READ_LOCK_REPORTING_THRESHOLD_MS_DEFAULT; @@ -113,7 +115,8 @@ public Long initialValue() { @VisibleForTesting FSNamesystemLock(Configuration conf, MutableRatesWithAggregation detailedHoldTimeMetrics, Timer timer) { - boolean fair = conf.getBoolean("dfs.namenode.fslock.fair", true); + boolean fair = conf.getBoolean(DFS_NAMENODE_FSLOCK_FAIR_KEY, + DFS_NAMENODE_FSLOCK_FAIR_DEFAULT); FSNamesystem.LOG.info("fsLock is fair: " + fair); this.coarseLock = new ReentrantReadWriteLock(fair); this.timer = timer; diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml b/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml index dbf78fcf30..0f72041b98 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml +++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml @@ -2759,6 +2759,16 @@ + + dfs.namenode.fslock.fair + true + If this is true, the FS Namesystem lock will be used in Fair mode, + which will help to prevent writer threads from being starved, but can provide + lower lock throughput. See java.util.concurrent.locks.ReentrantReadWriteLock + for more information on fair/non-fair locks. + + + dfs.namenode.startup.delay.block.deletion.sec 0 diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSNamesystemLock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSNamesystemLock.java index 1af8bf79e8..7f9746d8f8 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSNamesystemLock.java +++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSNamesystemLock.java @@ -40,6 +40,7 @@ import java.util.regex.Pattern; import static org.junit.Assert.*; +import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_FSLOCK_FAIR_KEY; import static org.apache.hadoop.test.MetricsAsserts.assertCounter; import static org.apache.hadoop.test.MetricsAsserts.assertGauge; @@ -53,11 +54,11 @@ public class TestFSNamesystemLock { public void testFsLockFairness() throws IOException, InterruptedException{ Configuration conf = new Configuration(); - conf.setBoolean("dfs.namenode.fslock.fair", true); + conf.setBoolean(DFS_NAMENODE_FSLOCK_FAIR_KEY, true); FSNamesystemLock fsnLock = new FSNamesystemLock(conf, null); assertTrue(fsnLock.coarseLock.isFair()); - conf.setBoolean("dfs.namenode.fslock.fair", false); + conf.setBoolean(DFS_NAMENODE_FSLOCK_FAIR_KEY, false); fsnLock = new FSNamesystemLock(conf, null); assertFalse(fsnLock.coarseLock.isFair()); } @@ -103,7 +104,7 @@ public void testFSLockGetWaiterCount() throws InterruptedException { final int threadCount = 3; final CountDownLatch latch = new CountDownLatch(threadCount); final Configuration conf = new Configuration(); - conf.setBoolean("dfs.namenode.fslock.fair", true); + conf.setBoolean(DFS_NAMENODE_FSLOCK_FAIR_KEY, true); final FSNamesystemLock rwLock = new FSNamesystemLock(conf, null); rwLock.writeLock(); ExecutorService helper = Executors.newFixedThreadPool(threadCount);