Clicking on sessions occasionally will cause a momentary hang, seems to be arbitrary

[term srv]

Occasionally I will click on a fiddler session and the application will hang for like 10 seconds before it lets me see the session. I do not have a way to reproduce. Is it normal, and is there a way to stop it from happening?

Windows 7 x64
Telerik Fiddler Web Debugger (v4.6.2.32002)

[Eric Lawrence]

No, it's certainly not "normal", although numerous things could cause this. Do you have any extensions installed? What tab is active on the right side of the window? Does it ever happen when the active tab is not Inspectors?

[term srv]

I am 90% of the time using the inspectors tab with raw, although I don't recall when it happens which tab I'm on. I'll pay closer attention next time.

[Eric Lawrence]

Yeah, Raw is probably the worst possible Inspector to have active, because if you go through any large bodies, they go into Windows' RichText editor control which has all kinds of performance problems on large text, especially with data that isn't really text.

[term srv]

If there is a lot of data in the body I recall seeing a message like 'only first xxx bytes are shown, click here to show the rest'. Is there a way to adjust how many bytes are shown by default in the response body?

[Eric Lawrence]

From the Fiddler book:

The RAW Inspector replaces any null bytes with the Unicode replacement character (�) and as such can be used to view binary response bodies, although the HexView remains more suitable for that task. Because displaying large binary bodies in the textbox can require large amounts of CPU time and memory, the Inspector is configured to automatically truncate the display of large responses. The threshold at which truncation occurs is controlled by the Content-Type and four preferences: 

• fiddler.inspectors.request.raw.truncatebinaryat 
• fiddler.inspectors.request.raw.truncatetextat
• fiddler.inspectors.response.raw.truncatebinaryat 
• fiddler.inspectors.response.raw.truncatetextat

By default, binary Content-Types are truncated at 128 bytes, and text types are truncated at 262144 bytes. Truncation can be disabled using the context menu

[term srv]

Thank you for that information. I have since been playing around with clicking on some arbitrary sessions and I think I have some idea what is happening. When there is a session with a response body like 100k that is truncated to 128 bytes (call this session FOO) and then I click on a different session that has a response body of 0 bytes (has to be 0.. call this session BAR) then there is a momentary hang and I can see occasionally in the inspector window for a split second it is putting the response body from session FOO in the session BAR (ie session BAR headers and session FOO body) before removing that body. So I think there may be a bug.

I've attached a file that can be used to reproduce this. Switch to the inspector tab and choose raw for both request and response. Click on the png file with 112,145 response body. It loads fine. Now click on the png file with 0 response body and it will hang for a few seconds. Unfortunately this repro case I do not see that weird amalgamation of the two sessions that I talked about above, but it does demonstrate the hang.

[Eric Lawrence]

That's a great, ridiculous bug... thanks a ton for finding it! 

Filed https://fiddler.ideas.aha.io/ideas/FID-I-123

[term srv]

No problem, thanks for your help!