Re: Question on QTEMP and CGI Jobs

The answer to the question is still "no". You have to assume that a "CGI call" as described in the question is an HTTP request to a CGI program. There is no way that two (or more) concurrent "CGI calls" can access the same objects in QTEMP as they will both be handled by different jobs (or CGI threads if that is the preferred terminology). So Richard has a bug and he is barking up the wrong tree for the solution.

As an aside, apart from the very first request, *all* requests (in our world) use xmlHttpRequest (AJAX). How "aggressive" is that? :)

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Henrik Rützou
Sent: 04 March 2017 10:13
To: Web Enabling the IBM i (AS/400 and iSeries) <web400@xxxxxxxxxxxx>
Subject: Re: [WEB400] Question on QTEMP and CGI Jobs

Kevin

well, it may be understod that they share QTEMP since a call to PGMA from user 1 and thereafter call to PGMB from user 2 running under the same QZSRCGI shares the same QTEMP that belongs to the QZSRCGI and not PGMA or PGMB.

PS - I don't think you uses AJAX as agressivly as I, if you fires 4-5 unnested AJAX calls from the browser at the same time it will result in 4-5 QZSRCGI jobs handling the requests, in other word they aren't queued to the same QZSRCGI job.

Remember that persistence CGI was written way before AJAX where AJAX may run many independend sockets to the server at the same time.


On Sat, Mar 4, 2017 at 10:42 AM, Kevin Turner <kevin.turner@xxxxxxxxxxxxxx>
wrote:

So the even shorter answer to this question "Would there be any way
for two CGI calls at the same time to overlap the QTEMP libs ?"
is
"No!"

HTH

On 4 Mar 2017, at 09:08, Kevin Turner <kevin.turner@xxxxxxxxxxxxxx>

wrote:

There is nothing special or different about QTEMP when used in a CGI

thread. It's unique to the thread/job so nothing else can touch
objects in there other than that thread. Obviously you cannot rely on
storing a value in QTEMP on one request and retrieving it in another
request because (unless you use persistent CGI) each request can go to
a different thread (with a different instance of QTEMP).

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On 4 Mar 2017, at 05:58, Richard Schoen
<Richard.Schoen@xxxxxxxxxxxxxxx>

wrote:

We have an interesting scenario where a CGI job is using a data
area in

QTEMP for a temp value in a web app and there appears to be a random
issue where that value gets clobbered by another job. (At least that's
what we think is happening.)

My understanding is that each CGI call is synchronous and each

thread/program active job instance has its own copy of QTEMP library
so one call on a particular CGI job thread would have to complete
before it can be re-used by another call. Or if there is only 1 CGI
thread/job subsequent calls will block until the executing call has completed.

Is my understanding of this correct ?

Would there be any way for two CGI calls at the same time to
overlap

the QTEMP libs ?

Hope this makes sense.

Any thoughts appreciated.

Thanks.

Regards,

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