crash unsubscribing newsgroup [@ nsMsgDBEnumerator::PrefetchNext]



MailNews Core
Networking: NNTP
17 years ago
9 years ago


(Reporter: jay, Assigned: Bienvenu)


({crash, topcrash})

Windows NT
crash, topcrash

Firefox Tracking Flags

(Not tracked)


(crash signature)



17 years ago
This is a topcrasher with Mozilla 0.9.4.  It's happeing with all flavors of
Windows.  Here is the latest info from Talkback reports:

A recent incident:

Incident ID 35639793
Stack Signature nsMsgDBEnumerator::PrefetchNext 227d3256
Bug ID
Trigger Time 2001-09-20 06:33:38
Email Address
User Comments
Build ID 2001091311
Product ID Netscape6.20
Platform ID Win32
Trigger Reason Access violation
Stack Trace
[d:\builds\seamonkey\mozilla\mailnews\db\msgdb\src\nsMsgDatabase.cpp, line 2240]
[d:\builds\seamonkey\mozilla\mailnews\db\msgdb\src\nsMsgDatabase.cpp, line 2210]
[d:\builds\seamonkey\mozilla\mailnews\db\msgdb\src\nsNewsDatabase.cpp, line 250]
[d:\builds\seamonkey\mozilla\mailnews\news\src\nsNNTPNewsgroupList.cpp, line 238]
[d:\builds\seamonkey\mozilla\mailnews\news\src\nsNNTPProtocol.cpp, line 3419]
[d:\builds\seamonkey\mozilla\mailnews\news\src\nsNNTPProtocol.cpp, line 5136]
[d:\builds\seamonkey\mozilla\mailnews\base\util\nsMsgProtocol.cpp, line 246]
[d:\builds\seamonkey\mozilla\netwerk\base\src\nsStreamListenerProxy.cpp, line 188]
PL_HandleEvent [d:\builds\seamonkey\mozilla\xpcom\threads\plevent.c, line 591]
PL_ProcessPendingEvents [d:\builds\seamonkey\mozilla\xpcom\threads\plevent.c,
line 524]
_md_EventReceiverProc [d:\builds\seamonkey\mozilla\xpcom\threads\plevent.c, line

And some more user comments:

URL: es.comp.os.linux.misc
     (35567345)	Comments: For once  I know why/when this happened.I just set up a newsgroup
account  using  and subscribed to a pair of newsgroups. I
downloaded headers for the first group  but decided it wasn't what I wanted  and
clicked on unsubscribe for that
     (35567345)	Comments:  group in the left menu (where your mail folders are listed). Then
 I right clicked on the second group  and hit unsubscribe  and confirmed. While
I did this  Mozilla was downloading the headers  and just after confirming the
unsubscribe  it crashed.
     (35564769)	URL:
Comments: Unsubscribing from newsgroups by right-clicking on them and choosing 
     (35531304)	Comments: unsubscribing from a couple of newsgroups
     (35531266)	Comments: unsubscribing from a couple of newsgoups
     (35466564)	Comments: 1) Upgraded to 0.9.4 the day before.2) in mail2news  opened a news
server folder. It started contemplating the subscribed groups  some of which
hadd 500+ message headers still to download across my 33K link.3) While it was
doing this  I unsubscribed
     (35466564)	Comments:  from ~3 of those groups.The unsubscription went ok  but then a
minute or so later  it brought up the "how many headers to download" dialog. I
cancelled the first two  & then it crashed. I don't know if there were any other
such groups it had yet to get
     (35466564)	Comments:  to.
     (35465846)	Comments: Unsubscribing from last subscribed newsgroup on a nntp server


17 years ago
Keywords: crash, topcrash
This is actually bug 87686, but I'll mark that a dup of this, and just add steps
to reproduce here.
*** Bug 87686 has been marked as a duplicate of this bug. ***
Reproducible: Always
Steps to Reproduce:
1. Subscribe to a large/active newsgroup with more than 300 new headers.
2. Right click on the group.  Both the context menu and the dialog should
appear.  Do not click on anything else yet.
3. Unsubscribe from the group via the context menu.  The group will be removed
from the list, but the download dialog will remain visible and active.
4. Click "download" in the dialog.

Comment 4

16 years ago
I couldn't reproduce with stephend's steps, so here are the steps I used:

1. Subscribe to a large group, for example alt.politics
2. Click on alt.politics and hit "Delete" (to bring up the Unsubscribe dialog)
3. Now click OK in the unsubscribe dialog.

Now you hopefully only have the "Download Headers" dialog, and clicking Download
there will make us crash.

We are crashing in |nsMsgDBEnumerator::PrefetchNext()| because |GetRowCursor()|
returns a null mRowCursor.  We only check for successful return values, no

I tried to null-check in |nsMsgDBEnumerator::PrefetchNext()|, and accordingly
return a NS_ERROR_NULL_POINTER but that made mork crazy spitting out an
inifinite number of assertions.

This topcrash is a DB issue, so handing over to bienvenu.  Hope this info is useful.
Assignee: sspitzer → bienvenu

Comment 5

16 years ago
what's going on here, almost certainly, is that unsubscribe is deleting the
database out from under the code that's downloading headers.

Comment 6

16 years ago
I'm having trouble accessing talkback right now to see if this is still
occurring on recent builds.  Since it's a topcrash I'm changing the milestone
and the priority.  If someone has new information on this on 0.9.5 and later
builds, please update.

It sounds like we should try to solve this through the UI.  I'm sure we have
other bugs about not allowing right click to load folders.  If the newsgroup
didn't start loading, then hitting unsubscribe would not have been an issue.  I
don't know if we can tell if we're in the middle of loading a folder.  If we
can, then maybe we should let items like delete and unsubscribe fail.
Priority: -- → P1
Target Milestone: --- → mozilla0.9.6
Putterman, I think that is bug 30560.

Comment 8

16 years ago
I got through to talkback.  This was is still happening in 10/11 builds and is
getting hit a lot.
*** Bug 105506 has been marked as a duplicate of this bug. ***


16 years ago
Keywords: nsbeta1+
Blocks: 39584
No longer blocks: 39584

Comment 10

16 years ago
The most recent build with a crash is 10/12 and it's really only showing on the
branch build.  And, there were a lot of crashes happening.  Could this have been
fixed on the trunk since then?

Comment 11

16 years ago
i don't crash on the trunk( 2001-10-26 build), looks like it's gone (fixed:-)
This worksforme also.
Last Resolved: 16 years ago
Resolution: --- → WORKSFORME
I tried hwaara's testcase, and couldn't get my Win32 trunk to crash.  Also, I 
ran a Talkback query for http://climate/reports/searchstacksignature.cfm?
stacksig=nsMsgDBEnumerator%3A%3APrefetchNext, and found all of the crashers 
were either on the branch, or in the case of Marina's crash, 2001-10-12-05  
Netscape6.20.  I believe this to have gone away, based on all of the above 
information.  Verified worksforme (why did this just go away??)

Comment 14

16 years ago
I doubt this is fixed - I'll try to reproduce it later. Re-opening so I don't
Resolution: WORKSFORME → ---


16 years ago
Target Milestone: mozilla0.9.6 → mozilla0.9.7

Comment 15

16 years ago
jpatel, namachi, janc: is this still showing up in talkback for recent mozilla 

Comment 16

16 years ago
talkback hasn't seen this crash in a build newer than 10/22/01, assuming I'm
using it correctly, which makes me think this is fixed. I could not reproduce
this myself.
Last Resolved: 16 years ago16 years ago
Resolution: --- → WORKSFORME
Summary: M094 crash unsubscribing newsgroup [@ nsMsgDBEnumerator::PrefetchNext] → crash unsubscribing newsgroup [@ nsMsgDBEnumerator::PrefetchNext]

This is FIXED.  Talkback confirms it.
Product: MailNews → Core
Product: Core → MailNews Core
Crash Signature: [@ nsMsgDBEnumerator::PrefetchNext]
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