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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Delphi’ Category

“Use TXSxxxx classes for simple nillable types”

Posted by jpluimers on 2019/10/08

For my link archive:

The first one missed these:

Both find these:

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, SOAP/WebServices, Software Development | Leave a Comment »

How to properly cleanup/shutdown a Delphi ISAPI (which uses Threads) | Mathias Pannier programmiert

Posted by jpluimers on 2019/10/03

For my link archive:

If you use Threads or global Objects (which are created in the initialization section for example) You have to cleanup/shutdown them in the OnTerminate event of the ISAPI Application. If You destroy/shutdown them in the finalization section in a unit it could end up in a hanging application pool in IIS on shutdown/reuse and some windows event log entries.

//added
procedure DoTerminate;
begin
  //free global objects and wait/terminate threads here
end;
exports
  GetExtensionVersion,
  HttpExtensionProc,
  TerminateExtension;
begin
  ReportMemoryLeaksOnShutdown := true;
  CoInitFlags := COINIT_MULTITHREADED;
  Application.Initialize;
  Application.WebModuleClass := WebModuleClass;
  TISAPIApplication(Application).OnTerminate := DoTerminate; //added
  Application.Run;
end.

Source [WayBack] How to properly cleanup/shutdown a Delphi ISAPI (which uses Threads) | Mathias Pannier programmiert

Related:

–jeroen

Posted in Delphi, Development, IIS, Software Development | Leave a Comment »

Delphi; on my research list `Error creating form: Root class not found: “”.`

Posted by jpluimers on 2019/10/03

On my Delphi research list:

[Window Title]
Error

[Content]
Error creating form: Root class not found: "".

[OK]

I think it has to do with form inheritance, but a quick glance didn’t raise any warning signs.

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | 1 Comment »

Terminate threads during application or not?

Posted by jpluimers on 2019/10/02

I got an interesting question a while ago: should an application terminate (anonymous) threads or not?

A problem is that a thread might not execute unless you call WaitFor before Terminate is called. The reason is that the internal function ThreadProc does not start Execute if the thread is already terminated.

The ThreadProc in the System.Classes unit is an ideal place to set breakpoints in order to see which threads might start.

Other useful places to set breakpoints:

  • TAnonymousThread.Execute
  • TExternalThread.Execute

Execute not being called by ThreadProc is a bug, but it is not documented because QC is gone (taking the below entry with it), it is not in QP and the docwiki never got updated.

Given QC has so much information, I am still baffled that Embarcadero took it down.

Sergey Kasandrov (a.k.a. serg or sergworks) wrote in [WayBack] Sleep sort and TThread corner case | The Programming Works about this bug and refers to WayBack: QualityCentral 35451 – TThread implementation doesn’t guarantee that thread’s Execute method will be called at all .

The really bad thing are the WayBack: QualityCentral Resolution Entries for Report #35451 Resolution “As Designed” implying the design is wrong.

In his post, sergworks implemented the Sleep sorting in Delphi. Related:

Note that application shutdown is a much debated topic. Best is to do as little cleanup as possible: your process is going to terminate soon anyway. No need to close handles or free memory: Windows will do that for you anyway. See for instance:

 

Related to waiting:

Related to executing:

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Multi-Threading / Concurrency, Software Development, The Old New Thing, Windows Development | Leave a Comment »

Soap Delphi Client end with a timeout for a 1MB call – Stack Overflow

Posted by jpluimers on 2019/09/26

This was a change between IE6 and IE7 on the default time-out decreasing from 3600 seconds to 30 seconds: [WayBack] Soap Delphi Client end with a timeout for a 1MB call – Stack Overflow.

If you want to increase the timeout, then use InternetSetOption. You can get the current value using InternetQueryOption.

In Delphi, THTTPReqResp.Send supports this by setting the various time out options right after creating the request:

    Request := HttpOpenRequest(FInetConnect, 'POST', PChar(FURLSite), nil,
                               nil, nil, Flags, 0{Integer(Self)});
    Check(not Assigned(Request));

    { Timeouts }
    if FConnectTimeout > 0 then
      Check(not InternetSetOption(Request, INTERNET_OPTION_CONNECT_TIMEOUT, Pointer(@FConnectTimeout), SizeOf(FConnectTimeout)));
    if FSendTimeout > 0 then
      Check(not InternetSetOption(Request, INTERNET_OPTION_SEND_TIMEOUT, Pointer(@FSendTimeout), SizeOf(FSendTimeout)));
    if FReceiveTimeout > 0 then
      Check(not InternetSetOption(Request, INTERNET_OPTION_RECEIVE_TIMEOUT, Pointer(@FReceiveTimeout), SizeOf(FReceiveTimeout)));

Related:

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, SOAP/WebServices, Software Development | Leave a Comment »

 
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