Web2 Ghost Sessions

Targets Web
1

Related discussion: 2021 R3.1 - Lost Connection Behavior Different? - #15 by Mike_D

I’ve added more debugging to my Web2 app and am seeing what appear to be “Ghost” sessions - these are sessions that exist for a long time, but do not have an active web page.

Here’s an example from this morning:

image

The first and last sessions are legit, but the middle 8 sessions are “ghost” ones. Oddly, they all were created at exactly the same time.

I’m not sure if this is a bug in 2021 R3.1 or something that I need to scan for and clean up myself?

Edit: oddly, the calculated session age is wrong, too.

I have this code:

Session.Opening
     createdMicroseconds = system.Microseconds

And yet if you back calculate the session age, 1969581 seconds is about 547 hours, which is how long since I last rebooted the server - this means createdMicroseconds = 0, and thus the session.Opening event never actually fired for these ghost sessions. Very odd.

2

Could they be sockets that are prepared but not connected yet (serversocket) ?
It seems very strange to have sessions for no use, wasting memory… ?

3

Interesting, if I look at my log, I do see a number of NilObjectExceptions that are being handled. Each one looks like this:

[2022-01-27 17:25:45] unknown : 82BDB8 Session.opening smith001 page='/' class='' opened from XX.XX.40.249 size=1280x567 browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:96.0) Gecko/20100101 Firefox/96.0
[2022-01-27 17:25:45] unknown : 82BDB8 smith001 Login cookie match
[2022-01-27 17:25:45] smith001 : 82BDB8 (cookie) login
[2022-01-27 17:26:00] smith001 : 82BDB8 disconnected
[2022-01-27 17:26:33] smith001 : 82BDB8  closing
[2022-01-27 17:26:33] [nil] App.UnhandledException (none) 0 : RuntimeRaiseException
      RaiseNilObjectException
      _WebPushHandler.CheckForChanges%%o<_WebPushHandler>
      _WebPushHandler.!Tickle
      _SessionShutdownThread.Event_Run%%o<_SessionShutdownThread>
      rbframework.dylib$6233
      rbframework.dylib$5961
      _pthread_body
      _pthread_body

It’s mostly happening with this single user ‘smith002’ who is on Firefox 96, and the # of ghost sessions is close to the # of times I see this in the log.

Maybe the ghost sessions are leftovers when Session.Closing is throwing this exception?

4

Looks like something is buggy here… Exception handling is slow so using that in a web framework would be a bad choice.

5

I’m able to reproduce this in the debugger now - the debugger breaks into SessionShutdownThread (but there is no code visible, presumably since it’s breaking into the framework). I’ll see if I can come up with a minimal reproducible case and file it.

6

Submitted as <https://xojo.com/issue/67519> with a demo project. It seems browser-specific, as I’m seeing it with Firefox 96 but not Safari.

1 Like
7

With Safari, I see a different issue, where Session.userTimedOut never fires.

Submitted as <https://xojo.com/issue/67520>

8

We have seen those in Web 1 and for us it’s a monitoring app used by the server admins, which tries to connect, but doesn’t load the website.

We ignore those and after 2 minutes such a session disappears, although it makes the server showing lots of those sessions at all times.