将数据流式传输到 gzip 文件会因“JavaScript 堆内存不足”（NodeJS）而崩溃

Question

我有这个小脚本可以以 gzip 的形式将一堆文本数据从源转储到磁盘。我从工作中提取的大多数资源都没有问题，但我遇到了一个抛出 JavaScript heap out of memory 的资源。

这是它正在做的事情的快照

const fs = require('fs');
const zlib = require('zlib');

const file = fs.createWriteStream('file.gz');
const gzip = zlib.createGzip();
gzip.pipe(file);

// ... code to connect to someDataSource would be here

someDataSource.on('data', (line) => { // feeding lines of text
    gzip.write(line);
});

someDataSource.on('done', () => {
    // crashes before this point
    gzip.end();
});

我怀疑zlib 模块在刷新到磁盘之前缓冲的方式比它应该的要多。在崩溃时，gz 文件只有大约4MB 大。就像我在上面所说的那样，我从工作中提取的其他数据源，所有这些都产生了远远超过 50MB 的 gz 文件。

模块上的文档在这里：https://nodejs.org/api/zlib.html#zlib_class_options

我不确定如何调整选项以使其正常运行。

崩溃：

<--- Last few GCs --->

[33692:0x10264e000]    97556 ms: Scavenge 1370.6 (1411.7) -> 1363.3 (1412.2) MB, 4.5 / 0.0 ms  (average mu = 0.174, current mu = 0.137) allocation failure 
[33692:0x10264e000]    97569 ms: Scavenge 1371.0 (1412.2) -> 1363.7 (1413.7) MB, 4.5 / 0.0 ms  (average mu = 0.174, current mu = 0.137) allocation failure 
[33692:0x10264e000]    97582 ms: Scavenge 1371.3 (1413.7) -> 1364.0 (1430.2) MB, 4.5 / 0.0 ms  (average mu = 0.174, current mu = 0.137) allocation failure 


<--- JS stacktrace --->

==== JS stack trace =========================================

    0: ExitFrame [pc: 0xdd88f3dbe3d]
Security context: 0x32b80cc1e6e9 <JSObject>
    1: /* anonymous */(aka /* anonymous */) [0x32b897904941] [/some/path/node_modules/tedious/lib/token/stream-parser.js:~154] [pc=0xdd88f6fbec4](this=0x32b8101826f1 <undefined>)
    2: valueParse(aka valueParse) [0x32b8c73a8ab9] [/some/path/node_modules/tedious/lib/value-parser.js:~74] [pc=0xdd88f6c96d3](this=0x32b8101826f1 ...

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
 1: 0x10003c597 node::Abort() [/usr/local/bin/node]
 2: 0x10003c7a1 node::OnFatalError(char const*, char const*) [/usr/local/bin/node]
 3: 0x1001ad575 v8::internal::V8::FatalProcessOutOfMemory(v8::internal::Isolate*, char const*, bool) [/usr/local/bin/node]
 4: 0x100579242 v8::internal::Heap::FatalProcessOutOfMemory(char const*) [/usr/local/bin/node]
 5: 0x10057bd15 v8::internal::Heap::CheckIneffectiveMarkCompact(unsigned long, double) [/usr/local/bin/node]
 6: 0x100577bbf v8::internal::Heap::PerformGarbageCollection(v8::internal::GarbageCollector, v8::GCCallbackFlags) [/usr/local/bin/node]
 7: 0x100575d94 v8::internal::Heap::CollectGarbage(v8::internal::AllocationSpace, v8::internal::GarbageCollectionReason, v8::GCCallbackFlags) [/usr/local/bin/node]
 8: 0x100574998 v8::internal::Heap::HandleGCRequest() [/usr/local/bin/node]
 9: 0x10052a1c8 v8::internal::StackGuard::HandleInterrupts() [/usr/local/bin/node]
10: 0x1007d9bb1 v8::internal::Runtime_StackGuard(int, v8::internal::Object**, v8::internal::Isolate*) [/usr/local/bin/node]
11: 0xdd88f3dbe3d 
12: 0xdd88f6fbec4 
13: 0xdd88f6c96d3 
14: 0xdd88f6c8870 
[1]    33692 abort      node app.js

Answer 1

添加一个排水事件监听器。因为将数据写入引导程序是一种同步行为。

someDataSource.on('data', (line) => { // feeding lines of text
    const ok = gzip.write(line);
    if(!ok) {
        someDataSource.pause();
    }
});
gzip.on('drain', () => {
    someDataSource.resume();
});

someDataSource.on('done', () => {
    // crashes before this point
    gzip.end();
});

或者直接使用pipe方法。

someDataSource.pipe(gzip).pipe(file);

Answer 2

你也可以尝试增加分配给 Node.js 的内存：

node --max-old-space-size=8192 your_script.js