HDFS-17630. Avoid PacketReceiver#MAX_PACKET_SIZE Initialized to 0.#8329
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balodesecurity wants to merge 1 commit intoapache:trunkfrom
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HDFS-17630. Avoid PacketReceiver#MAX_PACKET_SIZE Initialized to 0.#8329balodesecurity wants to merge 1 commit intoapache:trunkfrom
balodesecurity wants to merge 1 commit intoapache:trunkfrom
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The previous static initializer in PacketReceiver called new HdfsConfiguration(), which loads config resources via URL connections. If those URLs pointed to HDFS, the resulting class-loading chain could instantiate BlockReaderRemote before PacketReceiver finished initializing, causing the JVM to return the partially-initialized class with MAX_PACKET_SIZE == 0. Any subsequent block read then failed with "Incorrect value for packet payload size". Fix: initialize MAX_PACKET_SIZE directly to the compile-time default constant (removing the static initializer entirely) and introduce a static setMaxPacketSize(Configuration) method that DFSClient calls during construction to apply any configured override. This eliminates the circular class-loading dependency while preserving configurability. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
PacketReceiver.MAX_PACKET_SIZEwas set via astatic { new HdfsConfiguration(); ... }initializer. When config resources are loaded from HDFS URLs (e.g., during JAR loading viaURLJarFile), the resulting class-loading chain can instantiateBlockReaderRemotebeforePacketReceiverfinishes initializing. The JVM then returns the partially-initialized class withMAX_PACKET_SIZE == 0, causing every subsequent block read to throwIOException: Incorrect value for packet payload size.MAX_PACKET_SIZEdirectly to the compile-time default constant (eliminating the static initializer) and add a staticsetMaxPacketSize(Configuration)method thatDFSClientcalls during construction to apply any operator-configured override. This breaks the circular class-loading dependency while preserving configurability.Test plan
TestPacketReceiver#testMaxPacketSizeDefaultIsNonZeroandTestPacketReceiver#testSetMaxPacketSizeFromConfigpassTestPacketReceivertests continue to pass