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Revert to making IdentityHashCode#applyAsInt() synchronized for JDK 21 

patch by Caleb Rackliffe; reviewed by Dmitry Konstantinov for CASSANDRA-21213
This commit is contained in:
Caleb Rackliffe 2026-03-16 13:17:05 -05:00
parent 5bd164477f
commit a78504f541
2 changed files with 12 additions and 20 deletions
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29
test/simulator/main/org/apache/cassandra/simulator/systems/InterceptorOfGlobalMethods.java
View File

@ -21,7 +21,6 @@ package org.apache.cassandra.simulator.systems;
import java.util.ArrayDeque;
import java.util.UUID;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.IntSupplier;
import java.util.function.LongConsumer;
import java.util.function.ToIntFunction;
@ -488,7 +487,6 @@ public interface InterceptorOfGlobalMethods extends InterceptorOfSystemMethods,
private final IntSupplier nextId;
private final WeakIdentityHashMap<Object, Integer> saved = new WeakIdentityHashMap<>();
private final ReentrantLock mapLock = new ReentrantLock();
public IdentityHashCode(IntSupplier nextId)
{
@ -496,28 +494,19 @@ public interface InterceptorOfGlobalMethods extends InterceptorOfSystemMethods,
}
/**
* As {@link #saved} is not thread safe, we want to preserve weak reference semantics, and we want to gracefully
* support virtual threads, we need to use another locking mechanism other than synchronized since that is a risk
* of deadlock in JDK21 as virtual threads block on held monitors and won't release.
* As {@link #saved} is not thread safe, we want to preserve weak reference semantics. If we want to gracefully
* support virtual threads at some point, we need to use a locking mechanism other than synchronized, since that
* may introduce the risk of deadlock when virtual threads block on held monitors and won't release.
*/
public int applyAsInt(Object value)
public synchronized int applyAsInt(Object value)
{
mapLock.lock();
try
Integer id = saved.get(value);
if (id == null)
{
Integer id = saved.get(value);
if (id == null)
{
id = nextId.getAsInt();
saved.put(value, id);
}
return id;
}
finally
{
mapLock.unlock();
id = nextId.getAsInt();
saved.put(value, id);
}
return id;
}
}
}

3
test/simulator/test/org/apache/cassandra/simulator/test/SimulationTestBase.java
View File

@ -102,6 +102,9 @@ public class SimulationTestBase
@BeforeClass
public static void beforeAll()
{
// The shutdown threadcount invariant for normal tests does not apply to the Simulator
CassandraRelevantProperties.DTEST_IGNORE_SHUTDOWN_THREADCOUNT.setBoolean(true);
// Disallow time on the bootstrap classloader
for (CassandraRelevantProperties property : Arrays.asList(CLOCK_GLOBAL, CLOCK_MONOTONIC_APPROX, CLOCK_MONOTONIC_PRECISE))
property.setString("org.apache.cassandra.simulator.systems.SimulatedTime$Delegating");