[Netty 5] Default PooledByteBufAllocator configuration #8536
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👍 We override these in Finagle for the very same reason. |
normanmaurer
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Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to #8536.
normanmaurer
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…8991) Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to #8536.
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@chrisvest want to have a look ? |
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@normanmaurer Yeah, I'll make a note to look at this soon. |
chrisvest
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… MiB Motivation: By default we allocate 2 arenas per core, and each arena that is put to use will allocate a chunk. If we don't need a lot of memory, and certainly not compared to the number of cores on a system, then this will take up more memory than necessary, since each chunk is 16 MiB. By reducing the chunk size to 4 MiB, we reduce the minimum memory usage by a good deal, in these cases where not much is needed. The drawback is that we risk allocating more huge buffers, but this is a fair trade-off since Netty's use cases mostly involve very small buffers. Modification: Reduce the default max order from 11 to 9. Also make similar configuration changes in PooledByteBufAllocatorTest, to reduce the memory usage during testing. Result: Netty now uses less memory when less memory is needed by the application. This fixes netty#8536
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… MiB (#12108) Motivation: By default we allocate 2 arenas per core, and each arena that is put to use will allocate a chunk. If we don't need a lot of memory, and certainly not compared to the number of cores on a system, then this will take up more memory than necessary, since each chunk is 16 MiB. By reducing the chunk size to 4 MiB, we reduce the minimum memory usage by a good deal, in these cases where not much is needed. The drawback is that we risk allocating more huge buffers, but this is a fair trade-off since Netty's use cases mostly involve very small buffers. Modification: Reduce the default max order from 11 to 9. Also make similar configuration changes in PooledByteBufAllocatorTest, to reduce the memory usage during testing. Result: Netty now uses less memory when less memory is needed by the application. This fixes #8536
chrisvest
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Feb 28, 2022
…etty#8991) Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to netty#8536.
normanmaurer
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…8991) (#12109) Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to #8536. Co-authored-by: Norman Maurer <norman_maurer@apple.com>
raidyue
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… MiB (netty#12108) Motivation: By default we allocate 2 arenas per core, and each arena that is put to use will allocate a chunk. If we don't need a lot of memory, and certainly not compared to the number of cores on a system, then this will take up more memory than necessary, since each chunk is 16 MiB. By reducing the chunk size to 4 MiB, we reduce the minimum memory usage by a good deal, in these cases where not much is needed. The drawback is that we risk allocating more huge buffers, but this is a fair trade-off since Netty's use cases mostly involve very small buffers. Modification: Reduce the default max order from 11 to 9. Also make similar configuration changes in PooledByteBufAllocatorTest, to reduce the memory usage during testing. Result: Netty now uses less memory when less memory is needed by the application. This fixes netty#8536
raidyue
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…etty#8991) (netty#12109) Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to netty#8536. Co-authored-by: Norman Maurer <norman_maurer@apple.com>
franz1981
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… MiB (netty#12108) Motivation: By default we allocate 2 arenas per core, and each arena that is put to use will allocate a chunk. If we don't need a lot of memory, and certainly not compared to the number of cores on a system, then this will take up more memory than necessary, since each chunk is 16 MiB. By reducing the chunk size to 4 MiB, we reduce the minimum memory usage by a good deal, in these cases where not much is needed. The drawback is that we risk allocating more huge buffers, but this is a fair trade-off since Netty's use cases mostly involve very small buffers. Modification: Reduce the default max order from 11 to 9. Also make similar configuration changes in PooledByteBufAllocatorTest, to reduce the memory usage during testing. Result: Netty now uses less memory when less memory is needed by the application. This fixes netty#8536
franz1981
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…etty#8991) (netty#12109) Motivation: We currently use a thread local cache for all threads which often is suprising to users as it may result in a lot of memory usage if they allocate buffers from outside the EventLoop in different threads. We should better not do this by default to keep suprises to a minimum. Users that need the performance and know what they are doing can still change this. Modifications: Change io.netty.allocator.useCacheForAllThreads to false by default Result: Related to netty#8536. Co-authored-by: Norman Maurer <norman_maurer@apple.com>
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Default memory per chunk that the arena allocates is 16MB. We allocate 2 times number of arenas for direct and for heap buffers. This can be a large amount of memory for applications that may not need it. We should consider reducing the default values to reduce the initial memory footprint, and applications can tune the allocator if they need more chunks.
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