StephanEwen commented on a change in pull request #11018:
[FLINK-15905][runtime] Fix race condition between allocation and release of
OpaqueMemoryResource
URL: https://github.com/apache/flink/pull/11018#discussion_r375185846
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/memory/SharedResources.java
##########
@@ -80,27 +81,37 @@
}
}
+ /**
+ * Releases a lease (identified by the lease holder object) for the
given type.
+ * If no further leases exist, the resource is disposed.
+ */
+ void release(String type, Object leaseHolder) throws Exception {
+ release(type, leaseHolder, (value) -> {});
+ }
+
/**
* Releases a lease (identified by the lease holder object) for the
given type.
* If no further leases exist, the resource is disposed.
*
- * @return True, if this was the last lease holder and the resource was
disposed.
+ * <p>This method takes an additional hook that is called when the
resource is disposed.
*/
- boolean release(String type, Object leaseHolder) throws Exception {
+ void release(String type, Object leaseHolder, Consumer<Long> releaser)
throws Exception {
lock.lock();
try {
- final LeasedResource resource =
reservedResources.get(type);
+ final LeasedResource<?> resource =
reservedResources.get(type);
if (resource == null) {
- return false;
+ return;
}
if (resource.removeLeaseHolder(leaseHolder)) {
- reservedResources.remove(type);
- resource.dispose();
- return true;
+ try {
+ reservedResources.remove(type);
+ resource.dispose();
+ }
+ finally {
+ releaser.accept(resource.size());
+ }
Review comment:
The double release of the "reservation" is actually guarded twice:
- `if (resource.removeLeaseHolder(leaseHolder))`: Only the last release of
a lease can trigger that.
- The memory manager itself has this under an "owner", so if no memory is
reserved under that owner, none can be released.
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