jgc_exporter

An exporter that can continuously analyze hotspot gc logs(Parallel, CMS, G1, ZGC, etc.)

Running the exporter

Run the exporter as standalone HTTP server, prefer native executable if available:

start with jar:

# jdk require: 11+
#  os require: linux, windows
sh bin/run.sh --jar

# background running
sh bin/run.sh --jar --daemon

start with native executable (only linux now, windows is on the way):

# os require: linux
sh bin/run.sh --native

# background running
sh bin/run.sh --native --daemon

A simple config.yml looks like below:

# wildcard pattern is allowed in any level of paths, most of the time you only need to modify this configuration
fileGlobPattern: /path/to/some*/*.log

Fetch the metrics:

http://0.0.0.0:5898/metrics

Configuration

Name	Description
hostPort	Host and port that http server binds, default is 0.0.0.0:5898
fileGlobPattern	Wildcard pattern of gc log file path, separate multiple paths with commas(,)
idleTimeout	Milliseconds before closing idle(no update) files, default is 1 hour
watchInterval	Time interval for scanning matching files (ms)
readInterval	Time to sleep between files reading empty (ms)

Metric

Name	type	labels	Description
jgc_log_lines_total	counter	path, host	Number of process log lines
jgc_event_duration_seconds	summary	path, host, category	Duration of GC events
jgc_event_pause_duration_seconds	summary	path, host, category	Duration of GC pause events
jgc_heap_occupancy_before_collection_bytes	gauge	path, host	Heap occupancy before collection
jgc_heap_occupancy_after_collection_bytes	gauge	path, host	Heap occupancy after collection

See more metrics related to specific garbage-collection algorithms.

Build

./mvnw clean package

Native build

The exporter can be converted into native executables by installing graalvm(17 and 21).

• native dynamic link:

./mvnw -Pnative clean package

• native static link with musl:

./mvnw -Pnative-static-musl clean package

Suggestions

Note: The lack of essential jvm flags may miss some indicators, so we recommend that you set up your target java process as follows:

• jdk8 and previous versions

-verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps

• jdk9 and later versions

-verbose:gc -Xlog:gc*=info,gc+heap=debug,gc+phases=debug:file=xxx/gc.log:t,tags

Contributing

The exporter is still iterating frequently, all contributions are welcome. If you want a new feature, please raise an issue first.