Merge branch 'cassandra-3.11' into trunk
diff --git a/CHANGES.txt b/CHANGES.txt
index 76cd271..d382650 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -56,6 +56,7 @@
* Upgrade Jackson to 2.9.10 (CASSANDRA-15867)
* Fix CQL formatting of read command restrictions for slow query log (CASSANDRA-15503)
Merged from 3.0:
+ * Avoid thread starvation, and improve compare-and-swap performance, in the slab allocators (CASSANDRA-15922)
* Add token to tombstone warning and error messages (CASSANDRA-15890)
* Fixed range read concurrency factor computation and capped as 10 times tpc cores (CASSANDRA-15752)
* Catch exception on bootstrap resume and init native transport (CASSANDRA-15863)
diff --git a/src/java/org/apache/cassandra/utils/memory/NativeAllocator.java b/src/java/org/apache/cassandra/utils/memory/NativeAllocator.java
index 61e8407..af8b750 100644
--- a/src/java/org/apache/cassandra/utils/memory/NativeAllocator.java
+++ b/src/java/org/apache/cassandra/utils/memory/NativeAllocator.java
@@ -218,11 +218,6 @@
private final AtomicInteger nextFreeOffset = new AtomicInteger(0);
/**
- * Total number of allocations satisfied from this buffer
- */
- private final AtomicInteger allocCount = new AtomicInteger();
-
- /**
* Create an uninitialized region. Note that memory is not allocated yet, so
* this is cheap.
*
@@ -237,34 +232,24 @@
/**
* Try to allocate <code>size</code> bytes from the region.
*
- * @return the successful allocation, or null to indicate not-enough-space
+ * @return the successful allocation, or -1 to indicate not-enough-space
*/
long allocate(int size)
{
- while (true)
- {
- int oldOffset = nextFreeOffset.get();
+ int newOffset = nextFreeOffset.getAndAdd(size);
- if (oldOffset + size > capacity) // capacity == remaining
- return -1;
+ if (newOffset + size > capacity)
+ // this region is full
+ return -1;
- // Try to atomically claim this region
- if (nextFreeOffset.compareAndSet(oldOffset, oldOffset + size))
- {
- // we got the alloc
- allocCount.incrementAndGet();
- return peer + oldOffset;
- }
- // we raced and lost alloc, try again
- }
+ return peer + newOffset;
}
@Override
public String toString()
{
return "Region@" + System.identityHashCode(this) +
- " allocs=" + allocCount.get() + "waste=" +
- (capacity - nextFreeOffset.get());
+ "waste=" + Math.max(0, capacity - nextFreeOffset.get());
}
}
diff --git a/src/java/org/apache/cassandra/utils/memory/SlabAllocator.java b/src/java/org/apache/cassandra/utils/memory/SlabAllocator.java
index 16cb45d..538cd3f 100644
--- a/src/java/org/apache/cassandra/utils/memory/SlabAllocator.java
+++ b/src/java/org/apache/cassandra/utils/memory/SlabAllocator.java
@@ -179,11 +179,6 @@
private final AtomicInteger nextFreeOffset = new AtomicInteger(0);
/**
- * Total number of allocations satisfied from this buffer
- */
- private final AtomicInteger allocCount = new AtomicInteger();
-
- /**
* Create an uninitialized region. Note that memory is not allocated yet, so
* this is cheap.
*
@@ -201,30 +196,20 @@
*/
public ByteBuffer allocate(int size)
{
- while (true)
- {
- int oldOffset = nextFreeOffset.get();
+ int newOffset = nextFreeOffset.getAndAdd(size);
- if (oldOffset + size > data.capacity()) // capacity == remaining
- return null;
+ if (newOffset + size > data.capacity())
+ // this region is full
+ return null;
- // Try to atomically claim this region
- if (nextFreeOffset.compareAndSet(oldOffset, oldOffset + size))
- {
- // we got the alloc
- allocCount.incrementAndGet();
- return (ByteBuffer) data.duplicate().position(oldOffset).limit(oldOffset + size);
- }
- // we raced and lost alloc, try again
- }
+ return (ByteBuffer) data.duplicate().position((newOffset)).limit(newOffset + size);
}
@Override
public String toString()
{
return "Region@" + System.identityHashCode(this) +
- " allocs=" + allocCount.get() + "waste=" +
- (data.capacity() - nextFreeOffset.get());
+ "waste=" + Math.max(0, data.capacity() - nextFreeOffset.get());
}
}
}
