In an application I'm currently developing, meant to run under RHEL5, I needed to ensure that no multiple instances were running, so I installed the UniqueInstance component:
http://sourceforge.net/projects/lazarus-ccr/files/Unique%20Instance/Unique%20Instance%200.2/

Under RHEL5, the only usable combination is:
Lazarus 9.26.2
FPC 2.2.2
i386-linux-gtk2

In this environment, using the TUniqueInstance component leads to this situation: the first instance runs properly, the second terminates with an EAccess error in Form Create, which isn't very nice. If the Component is not enabled at design time, even the first instance aborts the same way.
Is that something to be expected because of version too new/too old, wrong fpc version, gtk2 vs gtk, etc.?

I'd like to understand if the matter is worth further investigation or it's simpler to give up.

BTW UniqueInstanceRaw works perfectly, but I'd prefer a visual component on the design form, to make life easier to maintainers, provided this can be achieved with a reasonable effort.

Could someone point me in the right direction?

Thanks,

Giuliano

please publish a sample project and a stacktrace

Luiz

Luiz Americo Pereira Camara ha scritto:

To avoid attachment length problems, my zipped sandbox folder is available at:

http://www.copeca.it/colla/Sandbox.zip

where you can find project1 and project2, to help sort out the problems, together with Trace1.txt and Trace2.txt, which are the stack traces for project1 and project2.

Project1 is nothing but a form with only a TUniqueInstance component. If the component is enabled at design time, it works perfectly. If the component is not enabled at design time, see Trace1.txt. (stack trace of the first and only instance running)

In Project2 I tried to put in one by one all the components of my real application. Apparently the problem arises with the TMemo component, whose presence, together with TUniqueInstance, triggers the access violation (see Trace2.txt, which is the trace of the second instance running). A TMemo issue or a TUiniqueInstance issue?

Kind regards,

Giuliano

Giuliano Colla ha scritto:

For sake of completeness, I tested with gtk1 in a different platform (but with same Lazarus and fpc versions). No difference.

Giuliano

Thanks.

I fixed the issue on svn.

There's one issue pending that i'm working on it. See comments of http://lazarusroad.blogspot.com/2006/12/only-one-instance.html

Luiz

Luiz Americo Pereira Camara ha scritto:

Thanks, I'll get the svn and try to backport the fix to my Lazarus version. If I come out with a good idea, I'll submit it for the pending issue. If not, I'll patiently wait for someone brighter than me to find the solution...

Luiz Americo Pereira Camara ha scritto:

For your information, the link to svn in the wiki page is broken. After failing, I got the good one from blogspot. Now I'll test ASAP.

I already fixed the issue in svn. Now there's no know issue with it.

I'll fix the wiki after i do a release

Luiz