[38277] in Kerberos
Re: krb5 ccache of MEMORY type
daemon@ATHENA.MIT.EDU (Roman Semenov)
Sat Jun 30 00:10:33 2018
To: Greg Hudson <ghudson@mit.edu>, "kerberos@mit.edu" <kerberos@mit.edu>
From: Roman Semenov <rasemenov@yahoo.com>
Message-ID: <c0b6a138-4dc1-d30a-9ba1-f7f38c814734@yahoo.com>
Date: Fri, 29 Jun 2018 20:11:39 -0700
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Hello Greg,
Thank you so much for the response and the link to the existing bug
report. Now it makes sense.
Thanks again,
Roman
On 06/29/2018 12:54 PM, Greg Hudson wrote:
> On 06/29/2018 03:46 PM, Greg Hudson wrote:
>>> Everything works fine while krb5 FILE type of ccache is in use. ow I
>>> want to improve performance and switch to MEMORY type of ccache. And
>>> I start getting my app crashed intermittently.
>>
>> I'm not currently aware of a memory ccache bug which would account
>> for this.
>
> Of course, as soon as I sent this I thought to search the bug database
> and found this (my own bug report, which I had forgotten about):
>
> http://krbdev.mit.edu/rt/Ticket/Display.html?id=8202
>
> which is "memory ccache cursors are invalidated by initialize". Since
> using a ccache to get tickets implicitly iterates over it, that bug
> would account for the crashes you are seeing. Destroying a memory
> ccache also breaks other threads iterating over it.
>
> You can possibly work around this bug by generating a new memory
> ccache (with krb5_cc_new_unique()) each time you want to initialize
> one, and keeping track of the current ccache name or handle yourself.
> You would have to be careful about destroying old ones when another
> thread might still be using them, so this might be more trouble than
> it's worth.
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