[iotdb] branch master updated: Fix the risk of deadlock by WeakReference (#1968)

[ha...@apache.org]

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


The following commit(s) were added to refs/heads/master by this push:
     new 6a68db0  Fix the risk of deadlock by WeakReference (#1968)
6a68db0 is described below

commit 6a68db05cad289d86ce21481b13b941628c57a3f
Author: Benedict Jin <as...@apache.org>
AuthorDate: Mon Dec 14 16:14:48 2020 +0800

    Fix the risk of deadlock by WeakReference (#1968)
---
 .../org/apache/iotdb/db/engine/cache/TimeSeriesMetadataCache.java  | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/server/src/main/java/org/apache/iotdb/db/engine/cache/TimeSeriesMetadataCache.java b/server/src/main/java/org/apache/iotdb/db/engine/cache/TimeSeriesMetadataCache.java
index 8273476..62eee4b 100644
--- a/server/src/main/java/org/apache/iotdb/db/engine/cache/TimeSeriesMetadataCache.java
+++ b/server/src/main/java/org/apache/iotdb/db/engine/cache/TimeSeriesMetadataCache.java
@@ -20,9 +20,13 @@
 package org.apache.iotdb.db.engine.cache;
 
 import java.io.IOException;
+import java.lang.ref.WeakReference;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.WeakHashMap;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
@@ -60,6 +64,7 @@ public class TimeSeriesMetadataCache {
 
   private final ReadWriteLock lock = new ReentrantReadWriteLock();
 
+  private final Map<String, WeakReference<String>> devices = Collections.synchronizedMap(new WeakHashMap<>());
 
   private TimeSeriesMetadataCache() {
     if (CACHE_ENABLE) {
@@ -127,7 +132,7 @@ public class TimeSeriesMetadataCache {
       printCacheLog(true);
     } else {
       // allow for the parallelism of different devices
-      synchronized (key.device.intern()) {
+      synchronized (devices.computeIfAbsent(key.device, WeakReference::new)) {
         // double check
         lock.readLock().lock();
         try {