ssrLoadModule uses 4+ GB of memory when loading 50+ MB files and causes crash due to OOM

[FeldrinH]

Describe the bug

When using ssrLoadModule to load files, the memory required to load files appears to be very large. In my testing about 100x larger than the size of the file itself.

This is problematic in particular when attempting to load large JSON files or text files (using ?raw) for use on the server. On my computer the memory usage is so large that loading a 50 MB file causes node to crash due to running out of memory. On my older computer, which has 8 GB of RAM, it is even worse, with 30 MB and sometimes even 20 MB files causing a crash.

(I originally found this issue when trying to import a large JSON file in a SvelteKit endpoint and filed it as sveltejs/kit#8592)

Reproduction

https://github.com/FeldrinH/vite-oom-repro

Steps to reproduce

Run npm install followed by node --expose-gc test.js

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
    Memory: 8.23 GB / 15.69 GB
  Binaries:
    Node: 18.12.1 - C:\Program Files\nodejs\node.EXE
    npm: 9.1.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1266.0), Chromium (108.0.1462.76)
    Internet Explorer: 11.0.19041.1566

Used Package Manager

npm

Logs

C:\...\vite-oom-repro>node --expose-gc test.js
Loading progressively larger files and observing heap usage:

Loading 10 MB file
Loaded 10 MB file. Heap usage: ~1070 MB

Loading 20 MB file
04:52:16 [vite] page reload largefile_20mb.txt
Loaded 20 MB file. Heap usage: ~1931 MB

Loading 30 MB file
04:52:23 [vite] page reload largefile_30mb.txt
Loaded 30 MB file. Heap usage: ~2896 MB

Loading 40 MB file
04:52:33 [vite] page reload largefile_40mb.txt
Loaded 40 MB file. Heap usage: ~3903 MB

Loading 50 MB file
04:52:55 [vite] page reload largefile_50mb.txt

<--- Last few GCs --->

[8020:0000023BFFAE9880]    65299 ms: Scavenge 4044.7 (4113.7) -> 4043.9 (4136.5) MB, 19.2 / 0.0 ms  (average mu = 0.269, current mu = 0.228) allocation failure;
[8020:0000023BFFAE9880]    67745 ms: Mark-sweep 4059.6 (4136.5) -> 4059.6 (4136.5) MB, 2441.3 / 0.0 ms  (average mu = 0.167, current mu = 0.031) allocation failure; scavenge might not succeed


<--- JS stacktrace --->

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
 1: 00007FF76E9E1B7F node_api_throw_syntax_error+203775
 2: 00007FF76E961556 v8::internal::wasm::WasmCode::safepoint_table_offset+63558
 3: 00007FF76E9628C2 v8::internal::wasm::WasmCode::safepoint_table_offset+68530
 4: 00007FF76F4047F4 v8::Isolate::ReportExternalAllocationLimitReached+116
 5: 00007FF76F3EFB52 v8::Isolate::Exit+674
 6: 00007FF76F271BBC v8::internal::EmbedderStackStateScope::ExplicitScopeForTesting+124
 7: 00007FF76F27EE9D v8::internal::Heap::PublishPendingAllocations+1117
 8: 00007FF76F27BF27 v8::internal::Heap::PageFlagsAreConsistent+3367
 9: 00007FF76F26E657 v8::internal::Heap::CollectGarbage+2039
10: 00007FF76F285013 v8::internal::HeapAllocator::AllocateRawWithLightRetrySlowPath+2099
11: 00007FF76F2858BD v8::internal::HeapAllocator::AllocateRawWithRetryOrFailSlowPath+93
12: 00007FF76F2950F3 v8::internal::Factory::NewFillerObject+851
13: 00007FF76EF86825 v8::internal::DateCache::Weekday+1349
14: 00007FF76F4A1E81 v8::internal::SetupIsolateDelegate::SetupHeap+558193
15: 00007FF6EF6A1ED8

C:\...\vite-oom-repro>

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

It seems removing this line reduces the memory usage significantly.

vite/packages/vite/src/node/ssr/ssrTransform.ts

Line 264 in c56b954

let map = s.generateMap({ hires: true })

I guess this is related to Rich-Harris/magic-string#195, Rich-Harris/magic-string#217.

[FeldrinH]

That's the sourcemap generation, right? Would it be possible to disable sourcemap generation for JSON and ?raw imports? Since they are just static data they shouldn't really need a sourcemap.

[FeldrinH]

Looking at the code I get the impression that just disabling hires would reduce memory usage significantly, so maybe it would be possible to disable hires for JSON and ?raw imports.

[bluwy]

This seems to be much improved in Vite 4.5.0 now:

bjorn@Bjorns-MacBook-Pro vite-oom-repro % node --expose-gc test.js
Loading progressively larger files and observing heap usage:

Loading 10 MB file
Loaded 10 MB file. Heap usage: ~58 MB

Loading 20 MB file
Loaded 20 MB file. Heap usage: ~129 MB

Loading 30 MB file
2:18:02 PM [vite] page reload largefile_20mb.txt
2:18:02 PM [vite] page reload largefile_20mb.txt (x2)
Loaded 30 MB file. Heap usage: ~152 MB

Loading 40 MB file
2:18:04 PM [vite] page reload largefile_30mb.txt
2:18:06 PM [vite] page reload largefile_40mb.txt (x2)
2:18:06 PM [vite] page reload largefile_50mb.txt
2:18:06 PM [vite] page reload largefile_50mb.txt (x2)
Loaded 50 MB file. Heap usage: ~204 MB

Loading 60 MB file
2:18:09 PM [vite] page reload largefile_60mb.txt
2:18:09 PM [vite] page reload largefile_60mb.txt (x2)
Loaded 60 MB file. Heap usage: ~398 MB

Closing as it doesn't crash anymore.