Inplace Predict Java API (xgboost4j)

[viswanathk]

Hello.

I see that in the changelog for 1.1.0, a new API was added for thread safe prediction (inplace_predict). The current predict method exposed through xgboost4j is not thread safe, and hence marked as synchronized in the method.

Given that the inplace_predict can now do threadsafe prediction, what are the plans of adding this to the Java API? We use this library in a multithreaded Java application, and this can help boost performance.

Thanks,
Viswanath.

[trivialfis]

Would you like to open a PR for it? Inplace prediction means XGBoost has to digest external data directly. I'm not familiar with the ecosystem of Java so I don't know what data types to support.

[trivialfis]

Also after #5853 normal predict function should also be thread safe in xgboost native code.

[viswanathk]

Good to know about #5853, but looks like it might take a while before we see it in release, and inplace_predict already does the job. Do you think it will be faster to add the Java wrapper to the inplace, than #5853 waiting for to make it release?

Would you like to open a PR for it? Inplace prediction means XGBoost has to digest external data directly. I'm not familiar with the ecosystem of Java so I don't know what data types to support.

I will go over the required changes - although I am not sure on where the gotchas can potentially be.

[trivialfis]

It's a blocking PR for the next release and we are now squashing the next release, so I would say pretty soon.

I will go over the required changes

I can help with issues in C++. @CodingCat expressed interest in inplace prediction before. So maybe @CodingCat can provide some suggestions on related topics around JVM bindings.

[dozaza]

Hi guys,

I'm working an online XGBoost prediction service, and want to use Java Multi thread for better performance.

As C++ code has resolved thread safe feature, simply removing "synchronize" key word in Java "predict" method, could enable multi-thread prediction in Java Environment?

[trivialfis]

The C API is thread safe now. You need to check whether JAVA layer has additional states.

[viswanathk]

Java layer doesn't seem to maintain any state that get's updated on the predict flow. Raised the PR #6021

Who's the maintainer / reviewer for the Java package?

[fangpings]

Any update on this issue?

[sihanwang94]

Need this feature +1