Copilot commented on code in PR #12400:
URL: https://github.com/apache/gluten/pull/12400#discussion_r3560720183
##########
backends-velox/src/main/scala/org/apache/gluten/config/VeloxConfig.scala:
##########
@@ -534,10 +535,35 @@ object VeloxConfig extends ConfigRegistry {
val COLUMNAR_VELOX_FILE_HANDLE_CACHE_ENABLED =
buildStaticConf("spark.gluten.sql.columnar.backend.velox.fileHandleCacheEnabled")
.doc(
- "Disables caching if false. File handle cache should be disabled " +
- "if files are mutable, i.e. file content may change while file path
stays the same.")
+ "Enables caching of file handles to avoid repeated open/close overhead
on remote " +
+ "filesystems. Should be disabled if files are mutable, i.e. file
content may " +
+ "change while file path stays the same.")
.booleanConf
- .createWithDefault(false)
+ .createWithDefault(true)
+
+ val COLUMNAR_VELOX_NUM_CACHE_FILE_HANDLES =
+
buildStaticConf("spark.gluten.sql.columnar.backend.velox.numCacheFileHandles")
+ .doc(
+ "Maximum number of entries in the file handle cache. Each entry holds
an open " +
+ "file descriptor (local FS) or connection state (remote FS). Note
that on " +
+ "local filesystems, high values may approach the OS file descriptor
limit " +
+ "(ulimit -n). On remote object stores (S3, ABFS, GCS) entries
represent " +
+ "network connections/sockets rather than per-file OS file
descriptors, but " +
+ "they can still count toward OS resource limits (ulimit -n).")
+ .intConf
+ .checkValue(_ > 0, "must be a positive number")
+ .createWithDefault(10000)
Review Comment:
With file handle caching now enabled by default, a default max size of
10,000 cached handles can easily exceed typical per-process file descriptor
limits (often 1024/4096) on local/HDFS workloads, leading to runtime failures
like "Too many open files" when scanning many distinct files/partitions.
Consider lowering the default (or making it adaptive to ulimit / executor
slots) so that the new default-on behavior is safer out of the box, while still
allowing advanced users to raise it explicitly.
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