[英]A lot of WriteConflict errors with MongoDB transactions
我目前正在玩 MongoDB 4.1.4 的最新可用 docker 圖像中的事務(使用 Node 8.12.0 和 Mongoose 5.3.8 作為客戶端)。 我用 3 個 mongo 實例制作了一個簡單的副本集,一切正常,直到我在短時間內出現很多WriteConflict
錯誤。
我的代碼如下所示:
// name, value are strings
// date is current time
const session = await createAnalyticsTransaction(); // returns 'session'
// _id is pregenerated
var stat = await Logger.findById(_id).session(session);
if (stat) {
// do nothing if it already exists
return true;
}
await Logger.update({
_id
}, {
$setOnInsert: {
_id,
name,
created: date.toDate(),
modified: date.toDate()
}
}, {
session,
upsert: true
});
/*
var period = 'month';
var time = '2018-11';
await Analytics.update({
_id
}, {
$setOnInsert: {
_id,
name,
period,
time,
created: date.toDate()
},
$inc: inc
}, {
upsert: true,
session: session
});
*/
await session.commitTransaction();
await session.endSession();
到目前為止一切正常,直到我使用$inc
和$setOnInsert
取消對 Analytics 集合的更新插入的注釋並同時運行大約 1000 個操作。 這個想法是,如果尚未創建 Analytics 集合,則應創建它。 然后我開始收到很多MongoError: WriteConflict
錯誤的屬性errorLabels
有TransientTransactionError
。
我認為這是因為$inc
或upsert: true
? 有沒有人經歷過這個? 在這種情況下最好的解決方案是什么?
{ MongoError: WriteConflict
at /Users/akuzmenok/Zend/MeteorLingua/lingua-analytics/node_modules/mongodb-core/lib/connection/pool.js:581:63
at authenticateStragglers (/Users/akuzmenok/Zend/MeteorLingua/lingua-analytics/node_modules/mongodb-core/lib/connection/pool.js:504:16)
at Connection.messageHandler (/Users/akuzmenok/Zend/MeteorLingua/lingua-analytics/node_modules/mongodb-core/lib/connection/pool.js:540:5)
at emitMessageHandler (/Users/akuzmenok/Zend/MeteorLingua/lingua-analytics/node_modules/mongodb-core/lib/connection/connection.js:310:10)
at Socket.<anonymous> (/Users/akuzmenok/Zend/MeteorLingua/lingua-analytics/node_modules/mongodb-core/lib/connection/connection.js:453:17)
at emitOne (events.js:116:13)
at Socket.emit (events.js:211:7)
at addChunk (_stream_readable.js:263:12)
at readableAddChunk (_stream_readable.js:250:11)
at Socket.Readable.push (_stream_readable.js:208:10)
at TCP.onread (net.js:597:20)
=> awaited here:
at Function.Promise.await (/Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/promise_server.js:56:12)
at Promise.asyncApply (imports/lib/analytics.js:97:9)
at /Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/fiber_pool.js:43:40
=> awaited here:
at Function.Promise.await (/Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/promise_server.js:56:12)
at Promise.asyncApply (imports/lib/analytics.js:139:5)
at /Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/fiber_pool.js:43:40
=> awaited here:
at Function.Promise.await (/Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/promise_server.js:56:12)
at Promise.asyncApply (imports/lib/analytics.js:158:5)
at /Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/fiber_pool.js:43:40
=> awaited here:
at Function.Promise.await (/Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/promise_server.js:56:12)
at Promise.asyncApply (imports/lib/analytics.js:49:23)
at /Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/fiber_pool.js:43:40
=> awaited here:
at Function.Promise.await (/Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/promise_server.js:56:12)
at Promise.asyncApply (imports/lib/analytics.js:14:23)
at /Users/akuzmenok/.meteor/packages/promise/.0.11.1.1ugu6ow.mjjhg++os+web.browser+web.browser.legacy+web.cordova/npm/node_modules/meteor-promise/fiber_pool.js:43:40
errorLabels: [ 'TransientTransactionError' ],
operationTime: Timestamp { _bsontype: 'Timestamp', low_: 12, high_: 1541424838 },
ok: 0,
errmsg: 'WriteConflict',
code: 112,
codeName: 'WriteConflict',
'$clusterTime':
{ clusterTime: Timestamp { _bsontype: 'Timestamp', low_: 12, high_: 1541424838 },
signature: { hash: [Object], keyId: 0 } },
name: 'MongoError',
[Symbol(mongoErrorContextSymbol)]: {} }
另一個注意事項,我正在開始這樣的交易:
const session = await MongoAnalytics.startSession({ causalConsistency: true });
session.startTransaction({ readConcern: { level: 'snapshot' }, writeConcern: { w: 'majority' } });
您從數據庫讀取數據,然后更新它。 它看起來像:
DATA (state 0) <---
UPDATED DATA (state 1) --->
當您執行兩個異步調用時:
DATA (state 0) <---
DATA (state 0) <---
UPDATED DATA (state 1) --->
UPDATED DATA (state 1') ---> ERROR
它返回一個錯誤,因為數據的狀態改變了。 這就是交易應該如何工作。
為了避免訪問沖突,您可以實現自定義隊列系統。 或者捕獲錯誤並使用 setTimeout 和最大嘗試次數重新運行事務。
排隊系統:
DATA (state 0) <---
UPDATED DATA (state 1) --->
DATA (state 1) <---
UPDATED DATA (state 2) --->
重新運行系統
DATA (state 0) <---
DATA (state 0) <---
UPDATED DATA (state 1) --->
UPDATED DATA (state 1') ---> ERROR
DATA (state 1) <---
UPDATED DATA (state 2) --->
在成功和失敗中這樣做
session.endSession()
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