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HBASE-10344 Improve write performance by ignoring sync to hdfs when an asyncer's writes have been synced by other asyncer 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1558506 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Zhihong Yu 2014-01-15 18:49:55 +00:00
parent bbf242cdaf
commit 16943fe2ae
1 changed files with 16 additions and 10 deletions
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26
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
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@ -1203,6 +1203,15 @@ class FSHLog implements HLog, Syncable {
this.txidToSync = this.writtenTxid; this.txidToSync = this.writtenTxid;
} }
// if this syncer's writes have been synced by other syncer:
// 1. just set lastSyncedTxid
// 2. don't do real sync, don't notify AsyncNotifier, don't logroll check
// regardless of whether the writer is null or not
if (this.txidToSync <= syncedTillHere.get()) {
this.lastSyncedTxid = this.txidToSync;
continue;
}
// 2. do 'sync' to HDFS to provide durability // 2. do 'sync' to HDFS to provide durability
long now = EnvironmentEdgeManager.currentTimeMillis(); long now = EnvironmentEdgeManager.currentTimeMillis();
try { try {
@ -1221,16 +1230,13 @@ class FSHLog implements HLog, Syncable {
// 6. t6: AsyncSyncer 1 starts to use writer to do sync... before // 6. t6: AsyncSyncer 1 starts to use writer to do sync... before
// rollWriter set writer to the newly created Writer // rollWriter set writer to the newly created Writer
// //
// So when writer == null here: // Now writer == null and txidToSync > syncedTillHere here:
// 1. if txidToSync <= syncedTillHere, can safely ignore sync here; // we need fail all the writes with txid <= txidToSync to avoid
// 2. if txidToSync > syncedTillHere, we need fail all the writes with // 'data loss' where user get successful write response but can't
// txid <= txidToSync to avoid 'data loss' where user get successful // read the writes!
// write response but can't read the writes! LOG.fatal("should never happen: has unsynced writes but writer is null!");
if (this.txidToSync > syncedTillHere.get()) { asyncIOE = new IOException("has unsynced writes but writer is null!");
LOG.fatal("should never happen: has unsynced writes but writer is null!"); failedTxid.set(this.txidToSync);
asyncIOE = new IOException("has unsynced writes but writer is null!");
failedTxid.set(this.txidToSync);
}
} else { } else {
this.isSyncing = true; this.isSyncing = true;
writer.sync(); writer.sync();