bytedeco/javacpp

Struct memory allocation is slow

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#299 opened on May 13, 2019

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enhancementhelp wanted

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Description

I run a simple benchmark calling window API's GetSystemTime using JavaCpp's built-in windows API wrappers. This code allocates a struct, calls the native API and fetches some field from the struct:

		SYSTEMTIME systemtime = new SYSTEMTIME();
		windows.GetSystemTime(systemtime);
		return systemtime.wSecond();

Profiling shows that the first line takes >90% of the overall execution time

image

I believe that there is some space for optimization here. The same thing implemented with Bridj or JNR outperforms JNI+JavaCpp just because of faster allocation, see the benchmark at https://github.com/zakgof/java-native-benchmark.

Say, with Bridj allocation takes <50% of the overall time:

image

Contributor guide

Research direction
Examine the JavaCpp struct allocation mechanism in the 'Pointer' class and compare with Bridj's approach. Profile memory allocation to identify bottlenecks.
Tech stack
javacpp
Domain
tooling
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaC++Profiling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30