bytedeco/javacpp

Struct memory allocation is slow

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#299 opened on May 13, 2019

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 (9 comments) (0 reactions) (0 assignees)Java (4,279 stars) (620 forks)batch import
enhancementhelp wanted

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

Tech stack
javacpp
Domain
performanceapi
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaJavaCpp basicsProfiling toolsmemory allocation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the memory allocation of structs in JavaCpp, particularly the `new SYSTEMTIME()` call. Compare with Bridj's allocation strategy. Look at the `Pointer` and `AllocationManager` classes in the JavaCpp source to identify potential optimizations. Use the provided benchmark to validate improvements.
Struct memory allocation is slow · bytedeco/javacpp#299 | Good First Issue