josh-mckenzie commented on code in PR #1778:
URL: https://github.com/apache/cassandra/pull/1778#discussion_r943644100
##########
src/java/org/apache/cassandra/config/DatabaseDescriptor.java:
##########
@@ -4381,4 +4397,68 @@ public static void
setMinTrackedPartitionTombstoneCount(long value)
{
conf.min_tracked_partition_tombstone_count = value;
}
+
+ public static boolean getDumpHeapOnUncaughtException()
+ {
+ return conf.dump_heap_on_uncaught_exception;
+ }
+
+ /**
+ * @return Whether the path exists (be it created now or already prior)
+ */
+ private static boolean maybeCreateHeapDumpPath()
+ {
+ if (!conf.dump_heap_on_uncaught_exception)
+ return false;
+
+ Path heap_dump_path = getHeapDumpPath();
+ if (heap_dump_path == null)
+ {
+ logger.warn("Neither -XX:HeapDumpPath nor
cassandra.yaml:heap_dump_path are set; unable to create a directory to hold the
output.");
+ return false;
+ }
+ if (PathUtils.exists(Paths.get(conf.heap_dump_path)))
+ return true;
+ return
PathUtils.createDirectoryIfNotExists(Paths.get(conf.heap_dump_path));
+ }
+
+ /**
+ * As this is at its heart a debug operation (getting a one-shot heapdump
from an uncaught exception), we support
+ * both the more evolved cassandra.yaml approach but also the -XX param to
override it on a one-off basis so you don't
+ * have to change the full config of a node or a cluster in order to get a
heap dump from a single node that's
+ * misbehaving.
+ * @return the absolute path of the -XX param if provided, else the
heap_dump_path in cassandra.yaml
+ */
+ public static Path getHeapDumpPath()
+ {
+ RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
+ Optional<String> pathArg =
runtimeMxBean.getInputArguments().stream().filter(s ->
s.startsWith("-XX:HeapDumpPath=")).findFirst();
+
+ if (pathArg.isPresent())
+ {
+ Pattern HEAP_DUMP_PATH_SPLITTER = Pattern.compile("HeapDumpPath=");
+ String fullHeapPathString =
HEAP_DUMP_PATH_SPLITTER.split(pathArg.get())[1];
+ Path absolutePath = Paths.get(fullHeapPathString).toAbsolutePath();
+ Path basePath = fullHeapPathString.endsWith(".hprof") ?
absolutePath.subpath(0, absolutePath.getNameCount() - 1) : absolutePath;
+ return Paths.get("/").resolve(basePath);
+ }
+ if (conf.heap_dump_path == null)
+ throw new ConfigurationException("Attempted to get heap dump path
without -XX:HeapDumpPath or cassandra.yaml:heap_dump_path set.");
+ return Paths.get(conf.heap_dump_path);
+ }
+
+ public static void setDumpHeapOnUncaughtException(boolean enabled)
+ {
+ conf.dump_heap_on_uncaught_exception = enabled;
+ boolean pathExists = maybeCreateHeapDumpPath();
+
+ // In the good case, we're either disabling or we're enabled and the
path exists on disk just fine.
+ if (!enabled || pathExists)
+ logger.info("Setting dump_heap_on_uncaught_exception to {}",
enabled);
+ else
+ {
+ logger.error("Attempted to enable heap dump but cannot create the
requested path. Disabling.");
+ conf.dump_heap_on_uncaught_exception = false;
+ }
Review Comment:
_**Thank you**_. This code was aesthetically irritating the hell out of me
but I kept bulldozing forward on other stuff and just walked away from it
making me feel... annoyed... without going deep enough to figure out why.
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