[bookkeeper] branch master updated: Limit read-ahead bytes to the size of the read cache (#2647)

[mmerli]

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mmerli pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/bookkeeper.git


The following commit(s) were added to refs/heads/master by this push:
     new 3f1b739  Limit read-ahead bytes to the size of the read cache (#2647)
3f1b739 is described below

commit 3f1b73968d1b921646f5cfd2a249382da49a3392
Author: Matteo Merli <mme...@apache.org>
AuthorDate: Thu Mar 18 11:25:06 2021 -0700

    Limit read-ahead bytes to the size of the read cache (#2647)
    
    * Limit read-ahead bytes to the size of the read cache
    
    * Update 
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java
    
    Co-authored-by: lipenghui <peng...@apache.org>
    
    Co-authored-by: lipenghui <peng...@apache.org>
---
 .../bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java       | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git 
a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java
 
b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java
index 0ac898c..94904be 100644
--- 
a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java
+++ 
b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java
@@ -134,6 +134,8 @@ public class SingleDirectoryDbLedgerStorage implements 
CompactableLedgerStorage
 
     private static final long DEFAULT_MAX_THROTTLE_TIME_MILLIS = 
TimeUnit.SECONDS.toMillis(10);
 
+    private final long maxReadAheadBytesSize;
+
     public SingleDirectoryDbLedgerStorage(ServerConfiguration conf, 
LedgerManager ledgerManager,
             LedgerDirsManager ledgerDirsManager, LedgerDirsManager 
indexDirsManager, StateManager stateManager,
             CheckpointSource checkpointSource, Checkpointer checkpointer, 
StatsLogger statsLogger,
@@ -155,6 +157,9 @@ public class SingleDirectoryDbLedgerStorage implements 
CompactableLedgerStorage
         readCacheMaxSize = readCacheSize;
         readAheadCacheBatchSize = conf.getInt(READ_AHEAD_CACHE_BATCH_SIZE, 
DEFAULT_READ_AHEAD_CACHE_BATCH_SIZE);
 
+        // Do not attempt to perform read-ahead more than half the total size 
of the cache
+        maxReadAheadBytesSize = readCacheMaxSize / 2;
+
         long maxThrottleTimeMillis = 
conf.getLong(DbLedgerStorage.MAX_THROTTLE_TIME_MILLIS,
                 DEFAULT_MAX_THROTTLE_TIME_MILLIS);
         maxThrottleTimeNanos = 
TimeUnit.MILLISECONDS.toNanos(maxThrottleTimeMillis);
@@ -469,7 +474,9 @@ public class SingleDirectoryDbLedgerStorage implements 
CompactableLedgerStorage
             int count = 0;
             long size = 0;
 
-            while (count < readAheadCacheBatchSize && currentEntryLogId == 
firstEntryLogId) {
+            while (count < readAheadCacheBatchSize
+                    && size < maxReadAheadBytesSize
+                    && currentEntryLogId == firstEntryLogId) {
                 ByteBuf entry = entryLogger.internalReadEntry(orginalLedgerId, 
firstEntryId, currentEntryLocation,
                         false /* validateEntry */);