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GitHub - reactor/BlockHound: Java agent to detect blocking calls from non-blocki...

 5 years ago
source link: https://github.com/reactor/BlockHound
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README.md

BlockHound (experimental)

Travis CI

Java agent to detect blocking calls from non-blocking threads.

How it works

BlockHound will transparently instrument the JVM classes and intercept blocking calls (e.g. IO) if they are performed from threads marked as "non-blocking operations only" (ie. threads implementing Reactor's NonBlocking marker interface, like those started by Schedulers.parallel()). If and when this happens (but remember, this should never happen!?), an error will be thrown. Here is an example:

// Example.java
BlockHound.install();

Mono.delay(Duration.ofSeconds(1))
    .doOnNext(it -> {
        try {
            Thread.sleep(10);
        }
        catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    })
    .block();

Will result in:

java.lang.Error: Blocking call! java.lang.Thread.sleep
	at java.base/java.lang.Thread.sleep(Native Method)
	at com.example.Example.lambda$exampleTest$0(Example.java:16)

Note that it points to the exact place where the blocking call got triggered. In this example it was Example.java:16.

Getting it

Download it from Maven Central repositories (stable releases only) or repo.spring.io:

repositories {
  maven { url 'https://repo.spring.io/milestone' }
  // maven { url 'https://repo.spring.io/snapshot' }
}

dependencies {
  testCompile 'io.projectreactor.tools:blockhound:$LATEST_RELEASE'
  // testCompile 'io.projectreactor.tools:blockhound:$LATEST_SNAPSHOT'
}

Where:

$LATEST_RELEASE $LATEST_SNAPSHOT

Quick Start

See the docs.

Licensed under Apache Software License 2.0

Sponsored by Pivotal


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