Victsm commented on a change in pull request #25907: [SPARK-29206][SHUFFLE]
Make number of shuffle server threads a multiple of number of chunk fetch
handler threads.
URL: https://github.com/apache/spark/pull/25907#discussion_r328350024
##########
File path:
common/network-common/src/main/java/org/apache/spark/network/util/TransportConf.java
##########
@@ -111,8 +111,30 @@ public int numConnectionsPerPeer() {
/** Requested maximum length of the queue of incoming connections. Default
is 64. */
public int backLog() { return conf.getInt(SPARK_NETWORK_IO_BACKLOG_KEY, 64);
}
- /** Number of threads used in the server thread pool. Default to 0, which is
2x#cores. */
- public int serverThreads() { return
conf.getInt(SPARK_NETWORK_IO_SERVERTHREADS_KEY, 0); }
+ /**
+ * The configured ratio between number of server threads and number of chunk
fetch handler
+ * threads. Default to 1, which sets the size of both thread pools to be
equal. Number of
+ * server threads needs to be a multiple of this ratio. See SPARK-29206.
+ */
+ private int getChunkFetchHandlerThreadsRatio() {
+ return conf.getInt("spark.shuffle.server.chunkFetchHandlerThreadsRatio",
1);
+ }
+
+ /**
+ * Number of threads used in the server thread pool. Default to 0, which is
2x#cores.
+ * If spark.shuffle.server.chunkFetchHandlerThreadsRatio is configured, and
the Netty server
+ * is for shuffle, then the actual # of server threads will round up to the
nearest int that
+ * is a multiple of the configured ratio.
+ */
+ public int serverThreads() {
+ int configuredServerThreads =
conf.getInt(SPARK_NETWORK_IO_SERVERTHREADS_KEY, 0);
+ if (this.getModuleName().equalsIgnoreCase("shuffle")) {
+ int chunkFetchHandlerThreadsRatio = getChunkFetchHandlerThreadsRatio();
+ return (int) Math.ceil(configuredServerThreads /
(chunkFetchHandlerThreadsRatio * 1.0));
Review comment:
If the server threads is 0, the logic in this patch would configure the
number of chunk fetch handler threads to be 2 * # cores. The current default
behavior would set server threads to 2 * # cores and set the percent to 100%.
So the number of chunk fetch handler threads is also 2 * # cores.
Line 362-363 in this patch:
return this.serverThreads() > 0 ? this.serverThreads() /
chunkFetchHandlerThreadsRatio :
2 * NettyRuntime.availableProcessors();
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