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[#3888] Use 2 * cores as default minimum for pool arenas.

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Motivation:

At the moment we use 1 * cores as default mimimum for pool arenas. This can easily lead to conditions as we use 2 * cores as default for EventLoop's when using NIO or EPOLL. If we choose a smaller number we will run into hotspots as allocation and deallocation needs to be synchronized on the PoolArena.

Modifications:

Change the default number of arenas to 2 * cores.

Result:

Less conditions when using the default settings.
This commit is contained in:
Norman Maurer 2015-06-17 09:39:54 +02:00
parent 29ac2ae3c2
commit e0ef01cf93
1 changed files with 9 additions and 3 deletions
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12
buffer/src/main/java/io/netty/buffer/PooledByteBufAllocator.java
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@ -69,18 +69,24 @@ public class PooledByteBufAllocator extends AbstractByteBufAllocator {
// Determine reasonable default for nHeapArena and nDirectArena.
// Assuming each arena has 3 chunks, the pool should not consume more than 50% of max memory.
final Runtime runtime = Runtime.getRuntime();
// Use 2 * cores by default to reduce condition as we use 2 * cores for the number of EventLoops
// in NIO and EPOLL as well. If we choose a smaller number we will run into hotspots as allocation and
// deallocation needs to be synchronized on the PoolArena.
// See https://github.com/netty/netty/issues/3888
final int defaultMinNumArena = runtime.availableProcessors() * 2;
final int defaultChunkSize = DEFAULT_PAGE_SIZE << DEFAULT_MAX_ORDER;
DEFAULT_NUM_HEAP_ARENA = Math.max(0,
SystemPropertyUtil.getInt(
"io.netty.allocator.numHeapArenas",
(int) Math.min(
runtime.availableProcessors(),
Runtime.getRuntime().maxMemory() / defaultChunkSize / 2 / 3)));
defaultMinNumArena,
runtime.maxMemory() / defaultChunkSize / 2 / 3)));
DEFAULT_NUM_DIRECT_ARENA = Math.max(0,
SystemPropertyUtil.getInt(
"io.netty.allocator.numDirectArenas",
(int) Math.min(
runtime.availableProcessors(),
defaultMinNumArena,
PlatformDependent.maxDirectMemory() / defaultChunkSize / 2 / 3)));
// cache sizes