Configuring the heap dump directory
Analyzing the heap dump file can help troubleshoot memory problems.
Java starts with the option -XX:+HeapDumpOnOutOfMemoryError.
Using this option triggers a heap dump in the event of an out-of-memory condition.
The heap dump file consists of references to objects that cause the heap to overflow.
By default, the database puts the file a subdirectory of the working, root directory when running as a service.
If the database does not have write permission to the root directory, the heap dump fails.
If the root directory is too small to accommodate the heap dump, the server crashes.
The DataStax Help Center also provides troubleshooting information.
To ensure that a heap dump succeeds and to prevent crashes, configure a heap dump directory that is:
-
Accessible to the database for writing
-
Large enough to accommodate a heap dump
Base the size of the directory on the value of the Java -mx option.
Procedure
Where is the cassandra-env.sh file?
The location of the cassandra-env.sh file depends on the type of installation:
| Installation Type | Location |
|---|---|
Package installations + Installer-Services installations |
|
Tarball installations + Installer-No Services installations |
|
-
Set the location of the heap dump in the
cassandra-env.shfile. -
Open the
cassandra-env.shfile for editing. -
Scroll down to the comment about the heap dump path:
# set jvm HeapDumpPath with CASSANDRA_HEAPDUMP_DIR if [ "x$CASSANDRA_HEAPDUMP_DIR" != "x" ]; then JVM_OPTS="$JVM_OPTS -XX:HeapDumpPath=$CASSANDRA_HEAPDUMP_DIR/cassandra-`date +%s`-pid$$.hprof" fi -
On the line after the comment, set the
CASSANDRA_HEAPDUMP_DIRto the desired path:# set jvm HeapDumpPath with CASSANDRA_HEAPDUMP_DIR export CASSANDRA_HEAPDUMP_DIR=path if [ "x$CASSANDRA_HEAPDUMP_DIR" != "x" ]; then JVM_OPTS="$JVM_OPTS -XX:HeapDumpPath=$CASSANDRA_HEAPDUMP_DIR/cassandra-`date +%s`-pid$$.hprof" fi -
Save the
cassandra-env.shfile and restart.
