Fix Exceptions are not handled on premain

[guhanjie]

Prev code would cause jvm to crash as Exception uncatched in javaagent premain. So this commit make the BindException checked and output definite error and then exit expectedly.

[guhanjie]

@dhoard could you please have a review?

[dhoard]

@guhanjie thanks for the PR! The change looks good.

Since it appears other types of Exceptions are not handled, maybe we should have a generic catch block to catch all possible exceptions, and change the IllegalArgumentException when parsing configuration to a ConfigurationException.

Thoughts?

try {
    // DO STUFF
} catch (Throwable t) {
    synchronized (System.err) {
        System.err.println("Failed to start Prometheus JMX Exporter");
        System.err.println();
        t.printStackTrace();
        System.err.println();
        System.err.println("Prometheus JMX Exporter exiting");
        System.err.flush();
    }
    System.exit(1);
}

[guhanjie]

@guhanjie thanks for the PR! The change looks good.

Since it appears other types of Exceptions are not handled, maybe we should have a generic catch block to catch all possible exceptions, and change the IllegalArgumentException when parsing configuration to a ConfigurationException.

Thoughts?

try {
    // DO STUFF
} catch (Throwable t) {
    synchronized (System.err) {
        System.err.println("Failed to start Prometheus JMX Exporter");
        System.err.println();
        t.printStackTrace();
        System.err.println();
        System.err.println("Prometheus JMX Exporter exiting");
        System.err.flush();
    }
    System.exit(1);
}

It sounds good, I update it, please hava a look again.

[guhanjie]

@dhoard Can you make a new release build and deploy to central mvn repository, because we are suffering such issue, and waiting for new release version CI, rather than local patch. Thanks~

[dhoard]

@guhanjie Can you elaborate on how you are suffering from this issue?

These exceptions should only happen on initial setup/configuration.

[guhanjie]

@guhanjie Can you elaborate on how you are suffering from this issue?

These exceptions should only happen on initial setup/configuration.

We are deploying our service using jmx_exporter java agent, which port may be used on some busy hosts, this would happen on large cluster, incident but crashed and have a heavy core dump file(20-30GB). That's not we expected.

[dhoard]

We are deploying our service using jmx_exporter java agent, which port may be used on some busy hosts, this would happen on large cluster, incident but crashed and have a heavy core dump file(20-30GB). That's not we expected.

You should define an application deployment standard (reserved port) for applications using the exporter.

I don't feel this change is worthy of a point release to work around what I feel is an anti-pattern for application deployment.