[英]Mongo call leading to node js memory leak
When I run await Order.find({})
, which returns 22k documents, the used_heap_size
goes up to around 430mb from around 50mb.当我运行
await Order.find({})
返回 22k 文档时, used_heap_size
从大约 50mb 增加到大约 430mb。
It never seems to go back down. go 似乎永远不会退缩。
Shouldn't the used_heap_size
go back down pretty soon? used_heap_size
go 不应该很快回落吗? I'm not sure if this is defined as a memory leak, but it seems like it.我不确定这是否被定义为 memory 泄漏,但似乎是这样。 What causes this?
这是什么原因造成的? Is this normal?
这是正常的吗?
app.get('/orders', async (req, res, next) => {
v8Print('before find orders');
const j = await Order.find({});
v8Print('afters find orders');
res.sendStatus(200);
});
app.get('/logMem', async (req, res, next) => {
v8Print('memory info');
res.sendStatus(200);
});
Log function记录 function
const v8 = require('v8');
// for memory allocation heap debugging
module.exports.v8Print = (message) => {
const heapStats = v8.getHeapStatistics();
const heapStatsMB = heapStats;
for (const key in heapStatsMB) {
heapStatsMB[key] = `${(((heapStatsMB[key] / 1024 / 1024) * 100) / 100).toFixed(2)} MB`;
}
console.log('');
console.log(message);
console.table(heapStatsMB);
console.log('');
};
before find orders
┌─────────────────────────────┬──────────────┐
│ (index) │ Values │
├─────────────────────────────┼──────────────┤
│ total_heap_size │ '54.05 MB' │
│ total_heap_size_executable │ '0.80 MB' │
│ total_physical_size │ '53.71 MB' │
│ total_available_size │ '1999.10 MB' │
│ used_heap_size │ '49.56 MB' │
│ heap_size_limit │ '2048.00 MB' │
│ malloced_memory │ '0.01 MB' │
│ peak_malloced_memory │ '2.48 MB' │
│ does_zap_garbage │ '0.00 MB' │
│ number_of_native_contexts │ '0.00 MB' │
│ number_of_detached_contexts │ '0.00 MB' │
└─────────────────────────────┴──────────────┘
afters find orders
┌─────────────────────────────┬──────────────┐
│ (index) │ Values │
├─────────────────────────────┼──────────────┤
│ total_heap_size │ '521.66 MB' │
│ total_heap_size_executable │ '1.05 MB' │
│ total_physical_size │ '520.90 MB' │
│ total_available_size │ '1611.12 MB' │
│ used_heap_size │ '435.79 MB' │ // <---435 after Orders.find
│ heap_size_limit │ '2048.00 MB' │
│ malloced_memory │ '0.01 MB' │
│ peak_malloced_memory │ '2.93 MB' │
│ does_zap_garbage │ '0.00 MB' │
│ number_of_native_contexts │ '0.00 MB' │
│ number_of_detached_contexts │ '0.00 MB' │
└─────────────────────────────┴──────────────┘
memory info
┌─────────────────────────────┬──────────────┐
│ (index) │ Values │
├─────────────────────────────┼──────────────┤
│ total_heap_size │ '521.66 MB' │
│ total_heap_size_executable │ '1.05 MB' │
│ total_physical_size │ '520.90 MB' │
│ total_available_size │ '1610.56 MB' │
│ used_heap_size │ '436.35 MB' │ // <--- stays around 435
│ heap_size_limit │ '2048.00 MB' │
│ malloced_memory │ '0.01 MB' │
│ peak_malloced_memory │ '2.93 MB' │
│ does_zap_garbage │ '0.00 MB' │
│ number_of_native_contexts │ '0.00 MB' │
│ number_of_detached_contexts │ '0.00 MB' │
└─────────────────────────────┴──────────────┘
V8 will only GC if it needs to free up space. V8 只有在需要释放空间时才会 GC。 By default Node is given ~2GB of memory so it's not under much pressure from your 435mb of objects.
默认情况下,Node 会获得约 2GB 的 memory,因此它不会受到 435mb 对象的太大压力。
You can force a GC by running your server as node --expose-gc server.js
which exposes a gc
function on the global.您可以通过将服务器作为
node --expose-gc server.js
运行来强制 GC,这会在全局上公开gc
function。
const v8 = require('v8');
// for memory allocation heap debugging
module.exports.v8Print = (message) => {
global.gc(); // <-- Call this before reading heap info
const heapStats = v8.getHeapStatistics();
const heapStatsMB = heapStats;
for (const key in heapStatsMB) {
heapStatsMB[key] = `${(((heapStatsMB[key] / 1024 / 1024) * 100) / 100).toFixed(2)} MB`;
}
console.log('');
console.log(message);
console.table(heapStatsMB);
console.log('');
};
// ...
app.get('/orders', async (req, res, next) => {
v8Print('before find orders'); // ~50MB
let j = await Order.find({}); // Use `let` merely so we can set it to `undefined` later
v8Print('afters find orders'); // ~435MB
j = undefined; // Remove reference so it can be GC'd
v8Print('afters clean up'); // ~50MB
res.sendStatus(200);
});
app.get('/logMem', async (req, res, next) => {
v8Print('memory info'); // ~50MB
res.sendStatus(200);
});
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