Using `crox --dir` to merge all trace files results in file that is not viewable in chromium performance tools

[wmmc88]

I get the following error when trying to open the resulting chrome_profiler.json file in performance tools: The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.

This only happens when merging all the traces via crox --dir. Single-crate generated file opens fine. Is there a max file size for opening the trace? the resulting merged chrome_profiler.json file I get is almost 5gb.

[bjorn3]

I am pretty sure the javascript heap used by V8 is restricted to 4GB. As such the profiler is unable to read your profile as it is simply way too big. Note that even with a <100MB profile it can already take several minutes for the chrome profiler to load it. Using the flamegraph util would likely work much better. Or you can use the stack_collapse util and load it in eg https://speedscope.app. Both utils will destroy the exact time when each sample happened, keeping only the time between samples and stack, allowing two samples with identical stack to be merged. This should save on most of the space usedby the final profile.