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https://github.com/honoluluhenk/gcmonitor
Help detect memory leaks and predict OutOfMemory situations
https://github.com/honoluluhenk/gcmonitor
Last synced: 1 day ago
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Help detect memory leaks and predict OutOfMemory situations
- Host: GitHub
- URL: https://github.com/honoluluhenk/gcmonitor
- Owner: HonoluluHenk
- License: mpl-2.0
- Created: 2019-05-14T05:23:39.000Z (over 5 years ago)
- Default Branch: develop
- Last Pushed: 2020-01-31T18:19:15.000Z (over 4 years ago)
- Last Synced: 2023-05-25T06:36:18.645Z (over 1 year ago)
- Language: Java
- Size: 173 KB
- Stars: 0
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# gc-monitor
[][Travis Link]
[][Maven Search Link]
Helps you detecting Garbage Collector overflows before they trash, crash or overwhelm the JVM.
# Usage
Maven dependency:
```xml
com.github.honoluluhenk.gcmonitor
gcmonitor
1.0.5
```
```java
// this will collect data from an OpenJDK compatible JVM.
// Information of the last 5 GC collections will get
// used for overflow detection:
// If the last 3 memory usage measures are above 80%,
// detection will return an overflow.
GCOverflowDetector detector = new GCOverflowDetector(
new OpenJDKEventSource(),
new CollectionSizeExpiry<>(5),
new UsageAboveThreshold(3, 80)
);
// actually start monitoring
detector.start();
// do some detection.
Overflow overflow = detector.detect();
// detect() may be called asynchronously and also multiple times.
// This allows implementing an external healthcheck easily.
if (overflow.getStatus() == Status.OVERFLOW) {
System.out.println("Got overflow, reason: " + overflow.getReason());
}
// cleanup
detector.stop();
```
The detector also supports re-use by calling `detector.start()` and `detector.stop()` repeatedly.
# GCOverflowDetector
Class: `GCOverflowDetector`
This is the main workhorse.
Tries to detect JVM memory overflows before they actually happen.
Uses Event Sources for memory usage data acquisition, Expiries for data removal and Detectors for the actual detection of memory overflows.
# Event Sources
## OpenJDKEventSource
Class: `OpenJDKEventSource`
Supports OpenJDK and compatible (Oracle, IBM, ...) JVMs.
# Expiries
# CollectionSizeExpiry
Class: `CollectionSizeExpiry`
Retains a maximum amount of measures. Older measures get expired first.
## DurationExpiry
Class: `DurationExpiry`
Keeps measures that are younger than some `TemporalAmount`.
## NullExpiry
Class: `NullExpiry`
Never expires anything. Mainly used for development since never expiring anything means a memory leak!
# Detectors
# UsageAboveThreshold
Class: `UsageAboveThreshold`
Takes N (1 <= N <= Integer.MAX_VALUE) memory usage readings. If *all* of these readings are above a threshold, an overflow is detected.
## AverageUsageAboveThreshold
Class: `AverageUsageAboveThreshold`
Works like UsageAboveThreshold but averages the memory usage over N memory usage readings.
If the averaged usage is above a threshold, an overflow is detected.
# Usage in application servers
This library requires the use of JDK internal classes in the package `com.sun.management`.
## JBoss Wildfly
Include the a system-dependency to the aforementioned package in a `jboss-deployment-structure.xml` file in your
deployment.
Example:
```xml
```
# Information for developers
## manual testing
A simple helper class with a main() method that produces a memory leak
is located ih [Tester.java](src/test/java/Tester.java)
Run the Tester with different JVM-parameters (e.g.: `-Xmx500m -XX:+UseG1GC`) to experience detection.
## Release
### Checklist
* check/update dependency version in README.md
### Execute
Bump version numbers, build with all checks enabled and - if successful - push everything:
```bash
mvn -U jgitflow:release-start jgitflow:release-finish
```
... and then wait for [Travis-CI][Travis Link].
[Travis Link]: https://travis-ci.org/HonoluluHenk/gcmonitor
[Maven Search Link]:
https://search.maven.org/search?q=g:%22com.github.honoluluhenk.gcmonitor%22%20AND%20a:%22gcmonitor%22