fastify
Store.set throwing in a promise crashes the application in Node v20
Prerequisites
- [X] I have written a descriptive issue title
- [X] I have searched existing issues to ensure the regression has not already been reported
Last working version
n.a.
Stopped working in version
n.a.
Node.js version
20.11.1
Operating system
macOS
Operating system version (i.e. 20.04, 11.3, 10)
14.3
💥 Regression Report
Having a set function in a custom store which rejects my app to crash in NodeJS v20. In versions before v20 (v18 / v16) this behaviour seemed to work just fine.
The actual application store connects to dynamodb which seems to throw whenever connections are aborted early:
store: {
get: (sessionId, callback) => {
server.DynamoDB.get({ TableName: TABLES.session, Key: { id: sessionId } }).then(
({ Item }) => callback(null, Item as any),
);
},
set: (sessionId, session, callback) => {
server.DynamoDB.put({
TableName: TABLES.session,
Item: {
...session,
id: sessionId,
},
}).then(() => callback());
},
destroy: (sessionId, callback) => {
server.DynamoDB.delete({ TableName: TABLES.session, Key: { id: sessionId } }).then(() =>
callback(),
);
},
},
Steps to Reproduce
I have created a repo with a minimal reproduction example.
The important file is src/server.ts which sets up the session middleware. To emulate dynamodb failing I have a let which I set to false, making the set function reject when a connection is interrupted.
Steps:
- Checkout repo
- move into repo
- nvm use
- npm i
- npm run start
- open separate terminal tab
- move into repo
- chmod +x ./scripts/test-load.sh && ./scripts/test-load.sh
- CTRL + C out of the script
- The application on the first tab crashed
If you change the nodejs version to v18.x (18.18.0 in my case) in the .nvmrc, reinstall, and retry the steps above you will see that the application won't crash.
Expected Behavior
The application does not crash.
I am not sure if this is intended behaviour, but it seemed off since it changes according to your nodejs version.
Also please keep in mind that the only purpose of the code in the attached repo is to reproduce the issue we were facing in proprietary code.
It does not produce the same error, but has the same behaviour as we have in our production code.
The error we received in our application was the following:
Error: Cannot write headers after they are sent to the client
at ServerResponse.writeHead (node:_http_server:345:11)
at onSendEnd (/node_modules/fastify/lib/reply.js:571:9)
at wrapOnSendEnd (/node_modules/fastify/lib/reply.js:537:5)
at next (/node_modules/fastify/lib/hooks.js:218:7)
at /node_modules/@fastify/session/lib/fastifySession.js:190:9
at /node_modules/@fastify/session/lib/session.js:171:9
at /src/plugins/sessions.ts:39:23
at processTicksAndRejections (node:internal/process/task_queues:95:5) {
code: 'ERR_HTTP_HEADERS_SENT'
}
Here, could you try this: https://github.com/niels-van-den-broeck/FastifyV20Repro/blob/a61a4aba1f4ac64e0edfb92231a6dfb1aaef2b67/src/server.ts#L46-L47
set: (sessionId, session, callback) => {
new Promise<void>((resolve, reject) => {
setTimeout(() => {
- if (cancelled) reject();
+ if (cancelled) { reject(); return };
resolve();
}, 150);
}).then(() => {
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
sessions.set(sessionId, {...session, id: sessionId });
callback();
});
},
I'm getting this error after upgrading from Node 19 to Node 22:
/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/standard-as-callback/built/index.js:6
throw e;
^
Error [ERR_HTTP_HEADERS_SENT]: Cannot write headers after they are sent to the client
at ServerResponse.writeHead (node:_http_server:345:11)
at safeWriteHead (/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/fastify/lib/reply.js:572:9)
at onSendEnd (/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/fastify/lib/reply.js:621:5)
at wrapOnSendEnd (/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/fastify/lib/reply.js:565:5)
at next (/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/fastify/lib/hooks.js:289:7)
at /filing-deadlines/node_modules/.pnpm/@[email protected]/node_modules/@fastify/session/lib/fastifySession.js:200:9
at /filing-deadlines/node_modules/.pnpm/@[email protected]/node_modules/@fastify/session/lib/session.js:180:11
at tryCatcher (/filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/standard-as-callback/built/utils.js:12:23)
at /filing-deadlines/node_modules/.pnpm/[email protected]/node_modules/standard-as-callback/built/index.js:22:53
at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
code: 'ERR_HTTP_HEADERS_SENT'
}
Node.js v22.2.0
I can't tell from that stack trace where the error originates. Is this an issue with the fastify session package, or an issue with my usage of it? It worked fine with previous versions of node.
Much appreciated
Here, could you try this: https://github.com/niels-van-den-broeck/FastifyV20Repro/blob/a61a4aba1f4ac64e0edfb92231a6dfb1aaef2b67/src/server.ts#L46-L47
set: (sessionId, session, callback) => { new Promise<void>((resolve, reject) => { setTimeout(() => { - if (cancelled) reject(); + if (cancelled) { reject(); return }; resolve(); }, 150); }).then(() => { // eslint-disable-next-line @typescript-eslint/ban-ts-comment // @ts-ignore sessions.set(sessionId, {...session, id: sessionId }); callback(); }); },
I have a solution, which is just catching the error DynamoDB throws in our application and calling the callback. I was just trying to point out the change in behaviour between Node versions.
In your original examples you were not handling errors, I'm actually surprised it even worked to begin with :D.
