No context available when using express-session with Memory store

[azatoth]

If using session and token middleware, trying to access the explorer crashes the server with a "Error: No context available. ns.run() or ns.bind() must be called first."

see also strongloop/loopback#2636 and https://github.com/azatoth/loopback-sandbox for a testcase (is also reproducible if using plain loopback-context 1.0.0 without the cls-hooked patch)

@bajtos

[azatoth]

As loopback is not using getCurrentContext() anymore but is accessing the raw loopbackContext object, there is no check if the context is active or not.

[bajtos]

So apparently the getCurrentContext checks for ns.active too. The patch strongloop/loopback#2604 which inlined getCurrentContext did not include this check.

[bajtos]

The problem is caused by the memory store provided by express-session, which calls setImmediate to defer callbacks - see session/memory.js#L25-L27. Apparently setImmediate is not supported by node-continuation-local-storage.

I agree loopback apps should not crash in such case, strongloop/loopback#2649 will fix that.

However, fixing express-session is up to somebody else to do.

[bajtos]

The problem is caused by the memory store provided by express-session, which calls setImmediate to defer callbacks - see session/memory.js#L25-L27. Apparently setImmediate is not supported by node-continuation-local-storage.

Let me clarify this. When I changed session/memory to use process.nextTick instead of setImmediate, then the app started to work. There may be something else in play, because node-continuation-local-storage claims to support setImmediate according to their docs (https://github.com/othiym23/node-continuation-local-storage#continuation-local-storage).

[Jeff-Lewis]

@bajtos have you had a chance to try cls-hooked? I'm curious if it helps with some of these known cls issues. The latest cls-hooked version supports node 4.5.0.

[azatoth]

@Jeff-Lewis initially I was testing with cls-hooked enabled (see https://github.com/azatoth/loopback-sandbox)

[bajtos]

@Jeff-Lewis there is a pending pull request reworking loopback-context to use cls-hooked, see #2

[josieusa]

cls-hooked depends on async-hook, which may supportsetImmediate, or at least so it seems from the source code. See https://github.com/AndreasMadsen/async-hook/blob/9c2d1ee927233ec1ad31cbf286029c1c98bd9885/patches/timers.js#L16

[josieusa]

Link to PR #11

[josieusa]

express-session is known to have problems with cls-hooked, see othiym23/node-continuation-local-storage#29. Maybe I could add tests for express-session to PR #19 to see if it solves the issue.

[stale]

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[stale]

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