Don't allocate memory when ensuring capacity

[felixbarny]

If you are having bad luck and the buffer is full while serializing a number, the buffer size doubles - even when the JsonWriter is underlying a target OutputStream. This has the potential to grow the buffer size indefinitely, leading to OOMEs.

See also this JMC screenshot from a flight recording which shows a huge allocation when calling NumberConverter#serialize(int, JsonWriter) ->
JsonWriter#ensureCapacity. I hope this can be fixed soon :)

I didn't get the tests to run so I couldn't test the change.

[zapov]

Tnx. What error do you get when running tests?

[felixbarny]

Wow, that was quick 😄

I get

java.lang.AssertionError: expected:<NOTE> but was:<ERROR>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:834)
	at org.junit.Assert.assertEquals(Assert.java:118)
	at org.junit.Assert.assertEquals(Assert.java:144)
	at com.dslplatform.json.DslValidationTest.checkNonNull(DslValidationTest.java:129)

My maven setup:

$ mvn -v
Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-17T20:33:14+02:00)
Maven home: /usr/local/Cellar/maven/3.5.4/libexec
Java version: 1.8.0_162, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.14.1", arch: "x86_64", family: "mac"

When do you plan to do the next release?

[zapov]

I was planing around months end. Waiting for #99 and maybe I'll look in some map stuff.

I've managed to reproduce the test issue on another machine. Tnx

[felixbarny]

Would it be possible to do a bugfix release a bit earlier? We just went GA with the Elastic APM Java agent (and are big fans of DSL-JSON). But I'm a bit concerned that this could cause OOMEs in user's applications.

[zapov]

Hm... ok. I'll look into releasing a new version early next week

[felixbarny]

That would be really great! Thank you!

[zapov]

I've released a new version just now. Please let me know if tests are working for you now.

[felixbarny]

Thanks! I'll have a look and release a bugfix for our agent.