我尝试将两个大的csv加载到nodejs中,第一个的大小为257 597 ko,第二个为104 330 ko。我使用的是文件系统(fs)和csv模块,下面是我的代码:
fs.readFile('path/to/my/file.csv', (err, data) => {
if (err) console.err(err)
else {
csv.parse(data, (err, dataParsed) => {
if (err) console.err(err)
else {
myData = dataParsed
console.log('csv loaded')
}
})
}
})
而在年龄(1-2小时)后,它只是崩溃与此错误消息:
<--- Last few GCs --->
[1472:0000000000466170] 4366473 ms: Mark-sweep 3935.2 (4007.3) -> 3935.2 (4007.
3) MB, 5584.4 / 0.0 ms last resort GC in old space requested
[1472:0000000000466170] 4371668 ms: Mark-sweep 3935.2 (4007.3) -> 3935.2 (4007.
3) MB, 5194.3 / 0.0 ms last resort GC in old space requested
<--- JS stacktrace --->
==== JS stack trace =========================================
Security context: 000002BDF12254D9 <JSObject>
1: stringSlice(aka stringSlice) [buffer.js:590] [bytecode=000000810336DC91 o
ffset=94](this=000003512FC822D1 <undefined>,buf=0000007C81D768B9 <Uint8Array map
= 00000352A16C4D01>,encoding=000002BDF1235F21 <String[4]: utf8>,start=0,end=263
778854)
2: toString [buffer.js:664] [bytecode=000000810336D8D9 offset=148](this=0000
007C81D768B9 <Uint8Array map = 00000352A16C4D01>,encoding=000002BDF1...
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memo
ry
1: node::DecodeWrite
2: node_module_register
3: v8::internal::FatalProcessOutOfMemory
4: v8::internal::FatalProcessOutOfMemory
5: v8::internal::Factory::NewRawTwoByteString
6: v8::internal::Factory::NewStringFromUtf8
7: v8::String::NewFromUtf8
8: std::vector<v8::CpuProfileDeoptFrame,std::allocator<v8::CpuProfileDeoptFrame
> >::vector<v8::CpuProfileDeoptFrame,std::allocator<v8::CpuProfileDeoptFrame> >
9: v8::internal::wasm::SignatureMap::Find
10: v8::internal::Builtins::CallableFor
11: v8::internal::Builtins::CallableFor
12: v8::internal::Builtins::CallableFor
13: 00000081634043C1
加载了最大的文件,但node的内存不足。分配更多的内存可能很容易,但这里的主要问题是加载时间,尽管文件很大,但它似乎很长。那么正确的方法是什么?Python使用pandas btw加载这些csv非常快(3-5秒)。
4条答案
按热度按时间xtupzzrd1#
流工作完美,它只花了3-5秒:
taor4pac2#
readFile将把整个文件加载到内存中,但是fs.createReadStream将按照您指定的大小分块读取文件。
这将防止它耗尽内存
wn9m85ua3#
您可能希望流式传输CSV,而不是一次阅读所有内容:
bwitn5fc4#
通过传递文件路径调用函数: