I’m working on speeding up a Node.js module that uses Cairo for image processing. The main problem is with Canvas.toBuffer(). It’s eating up our resources so I made a new way to change Canvas into an Image without using a png buffer.
But Cairo is tricky and there are worries about memory in node modules. I added HandleScopes to functions that use V8 data. The new Canvas.loadImage(image) method works fine on my Mac and in tests on our Ubuntu servers. But when it runs as a background process with Gearman we get memory errors and crashes.
Also I can’t call methods from node-canvas classes if they’re not in header files. How can I make shared native code packages for other node modules?
I tried to find the problem with debugging tools but the error happens in a library I can’t trace. Here’s a bit of my code:
void processImage(Image* img) {
int width = 800;
int height = 600;
uint8_t* buffer = new uint8_t[width * height * 4];
// Fill buffer with image data
for (int i = 0; i < width * height * 4; i++) {
buffer[i] = i % 256;
}
img->loadFromDataBuffer(buffer, width, height);
delete[] buffer;
}
Any tips or help would be great. Thanks!
Having dealt with similar issues, I’d suggest focusing on Cairo’s memory management. The crux might be in how Cairo handles surface creation and destruction. Ensure you’re explicitly freeing Cairo surfaces and contexts when they’re no longer needed.
For the Gearman crashes, consider the possibility of race conditions. Background processes can introduce timing-related bugs that don’t appear in standard tests. Implement proper synchronization mechanisms if multiple threads are accessing shared resources.
Regarding shared native code, you could create a separate shared library that both your module and node-canvas can link against. This approach allows you to expose the necessary functionality without directly accessing node-canvas internals.
Lastly, have you tried using a memory leak detector like mtrace or electric fence? These tools can pinpoint memory issues that standard debuggers might miss, especially in complex, multi-library setups.
Hey Sophia63, i’ve been there with node modules and memory issues. sounds like a pain! have u tried using a memory profiler like heapshot? it can help pinpoint leaks. also, make sure ur properly releasing resources in ur native code. sometimes its the little things that bite ya. good luck!
As someone who’s worked extensively with native C++ Node.js modules and Cairo, I can relate to your struggles. Memory management in this context can be a real headache.
One thing that jumps out at me is your use of raw pointers. Consider using smart pointers instead, like std::unique_ptr, to manage your buffer memory. This can help prevent leaks and make your code more exception-safe.
Also, have you tried using a memory profiler like Valgrind or Address Sanitizer? These tools can be invaluable for tracking down elusive memory issues, especially in complex setups involving multiple libraries.
For your issue with accessing node-canvas methods, you might want to look into using a pimpl idiom or creating a wrapper class that exposes the necessary functionality.
Lastly, ensure you’re properly managing the V8 context and isolate in your native code. Improper handling here can lead to subtle memory issues that only manifest under specific conditions, like your Gearman scenario.
Keep at it - native modules can be tricky, but the performance gains are often worth the effort!