Package org.apache.flink.runtime.io.network.buffer

Class LocalBufferPool

  • All Implemented Interfaces:
    AvailabilityProvider, BufferPool, BufferProvider, BufferRecycler
    public class LocalBufferPool
extends Object
implements BufferPool
    A buffer pool used to manage a number of Buffer instances from the NetworkBufferPool.

    Buffer requests are mediated to the network buffer pool to ensure deadlock free operation of the network stack by limiting the number of buffers per local buffer pool. It also implements the default mechanism for buffer recycling, which ensures that every buffer is ultimately returned to the network buffer pool.

    The size of this pool can be dynamically changed at runtime (setNumBuffers(int). It will then lazily return the required number of buffers to the NetworkBufferPool to match its new size.

    New buffers can be requested only when numberOfRequestedMemorySegments < currentPoolSize + maxOverdraftBuffersPerGate. In other words, all buffers exceeding the currentPoolSize will be dynamically regarded as overdraft buffers.

    Availability is defined as returning a non-overdraft segment on a subsequent requestBuffer()/ requestBufferBuilder() and heaving a non-blocking requestBufferBuilderBlocking(int). In particular,

    To ensure this contract, the implementation eagerly fetches additional memory segments from NetworkBufferPool as long as it hasn't reached maxNumberOfMemorySegments or one subpartition reached the quota.

    • Method Detail

      • reserveSegments

        public void reserveSegments​(int numberOfSegmentsToReserve)
                     throws IOException
        Description copied from interface: BufferPool
        Reserves the target number of segments to this pool. Will throw an exception if it can not allocate enough segments.
        Specified by:
        reserveSegments in interface BufferPool
        Throws:
        IOException

      • getNumberOfRequiredMemorySegments

        public int getNumberOfRequiredMemorySegments()
        Description copied from interface: BufferPool
        Returns the number of guaranteed (minimum number of) memory segments of this buffer pool.
        Specified by:
        getNumberOfRequiredMemorySegments in interface BufferPool

      • getMaxNumberOfMemorySegments

        public int getMaxNumberOfMemorySegments()
        Description copied from interface: BufferPool
        Returns the maximum number of memory segments this buffer pool should use.
        Specified by:
        getMaxNumberOfMemorySegments in interface BufferPool
        Returns:
        maximum number of memory segments to use or -1 if unlimited

      • getNumberOfRequestedMemorySegments

        @VisibleForTesting
public int getNumberOfRequestedMemorySegments()

      • getNumberOfAvailableMemorySegments

        public int getNumberOfAvailableMemorySegments()
        Description copied from interface: BufferPool
        Returns the number memory segments, which are currently held by this buffer pool.
        Specified by:
        getNumberOfAvailableMemorySegments in interface BufferPool

      • getNumBuffers

        public int getNumBuffers()
        Description copied from interface: BufferPool
        Returns the current size of this buffer pool.

        The size of the buffer pool can change dynamically at runtime.

        Specified by:
        getNumBuffers in interface BufferPool

      • bestEffortGetNumOfUsedBuffers

        public int bestEffortGetNumOfUsedBuffers()
        Description copied from interface: BufferPool
        Returns the number of used buffers of this buffer pool.
        Specified by:
        bestEffortGetNumOfUsedBuffers in interface BufferPool

      • requestBuffer

        public Buffer requestBuffer()
        Description copied from interface: BufferProvider
        Returns a Buffer instance from the buffer provider, if one is available.
        Specified by:
        requestBuffer in interface BufferProvider
        Returns:
        null if no buffer is available or the buffer provider has been destroyed.

      • requestBufferBuilder

        public BufferBuilder requestBufferBuilder​(int targetChannel)
        Description copied from interface: BufferProvider
        Returns a BufferBuilder instance from the buffer provider.
        Specified by:
        requestBufferBuilder in interface BufferProvider
        Parameters:
        targetChannel - to which the request will be accounted to.
        Returns:
        null if no buffer is available or the buffer provider has been destroyed.

      • requestMemorySegmentBlocking

        public org.apache.flink.core.memory.MemorySegment requestMemorySegmentBlocking()
                                                                        throws InterruptedException
        Description copied from interface: BufferProvider
        Returns a MemorySegment instance from the buffer provider.

        If there is no memory segment available, the call will block until one becomes available again or the buffer provider has been destroyed.

        Specified by:
        requestMemorySegmentBlocking in interface BufferProvider
        Throws:
        InterruptedException

      • requestMemorySegment

        public org.apache.flink.core.memory.MemorySegment requestMemorySegment()
        Description copied from interface: BufferProvider
        Returns a MemorySegment instance from the buffer provider.
        Specified by:
        requestMemorySegment in interface BufferProvider
        Returns:
        null if no memory segment is available or the buffer provider has been destroyed.

      • recycle

        public void recycle​(org.apache.flink.core.memory.MemorySegment segment)
        Description copied from interface: BufferRecycler
        Recycles the MemorySegment to its original BufferPool instance.
        Specified by:
        recycle in interface BufferRecycler
        Parameters:
        segment - The memory segment to be recycled.

      • lazyDestroy

        public void lazyDestroy()
        Destroy is called after the produce or consume phase of a task finishes.
        Specified by:
        lazyDestroy in interface BufferPool

      • addBufferListener

        public boolean addBufferListener​(BufferListener listener)
        Description copied from interface: BufferProvider
        Adds a buffer availability listener to the buffer provider.

        The operation fails with return value false, when there is a buffer available or the buffer provider has been destroyed.

        Specified by:
        addBufferListener in interface BufferProvider

      • setNumBuffers

        public void setNumBuffers​(int numBuffers)
        Description copied from interface: BufferPool
        Sets the current size of this buffer pool.

        The size needs to be greater or equal to the guaranteed number of memory segments.

        Specified by:
        setNumBuffers in interface BufferPool

      • setMaxOverdraftBuffersPerGate

        public void setMaxOverdraftBuffersPerGate​(int maxOverdraftBuffersPerGate)
        Description copied from interface: BufferPool
        Sets the max overdraft buffer size of per gate.
        Specified by:
        setMaxOverdraftBuffersPerGate in interface BufferPool