Inspecting Java services

Debug interface

The following RPC commands are available in the container for debugging purposes:

NameArgumentsResult
debug.dump-query-packets cluster-name, 0/1 (disable, enable) Dumps query packets to $VESPA_HOME/logs/vespa/qrs/qrs.<server-index>.<cluster-name>.query.dump
debug.dump-result-packets cluster-name, 0/1 (disable, enable) Dumps query packets to $VESPA_HOME/logs/vespa/qrs/qrs.<server-index>.<cluster-name>.result.dump
debug.output-search-chain search-chain-name Returns a human readable description of a given search chain and the search chains it forwards to
debug.backend-statistics cluster-name Returns (backend, active connections, total connections) tuples separated with the same order into three arrays
The commands can be called by using vespa-rpc-invoke (call it without arguments to get usage information). Example - output the searchers in a search chain:
$ vespa-rpc-invoke tcp/localhost:19102 debug.output-search-chain s:vespa

JConsole

Determine the state of each running Java Vespa service using JConsole. JConsole is distributed along with the Java developer kit. It can be started as follows:

$ jconsole <host>:<port>
where the host and port determine which service to attach to. For security purposes the JConsole tool can not directly attach to Vespa services from external machines.

Connecting to a Vespa instance

To attach a JConsole to a Vespa service running on another host, create a tunnel from the JConsole host to the Vespa service host. This can for example be done by setting up two SSH tunnels as follows:

$ ssh -N -L<port1>:localhost:<port1> <service-host> &
$ ssh -N -L<port2>:localhost:<port2> <service-host> &
where port1 and port2 are determined by the type of service (see below). A JConsole can then be attached to the service as follows:
$ jconsole localhost:<port1>
Port numbers:
Service Port 1 Port 2
QRS 19015 19016
Docproc 19123 19124
Updated port information can be found by running:
$ vespa-model-inspect service <servicename>
where the resulting RMIREGISTRY and JMX lines determine port1 and port2, respectively.

Examining thread states

The state of each container is available in JConsole by pressing the Threads tab and selecting the thread of interest in the threads list. Threads of interest includes search, connector, closer, transport and acceptor (the latter four are used for backend communications):

Thread states in JConsole.