BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Strange ADO issue doesn't happen in debug mode          BorlandTalk.com Forum Index -> C++ Builder Databases (ADO) View previous topic :: View next topic   Author Message Simon Elliott Guest Posted: Wed Sep 20, 2006 1:50 am    Post subject: Strange ADO issue doesn't happen in debug mode Hello ADO experts I'm using BCB6 with patch 4, and trying to create a MS Access database with ADO. My app works fine if compiled in debug mode, but has some nasty "accessing address xxxxx" style exceptions if compiled in release mode. I've reduced the app to a small consolde mode test app, and still happens. Any thougths? What's the best way to go about tracking this down? -- Simon Elliott http://www.ctsn.co.uk Back to top Clayton Arends Guest Posted: Sat Sep 23, 2006 7:11 pm    Post subject: Re: Strange ADO issue doesn't happen in debug mode "Simon Elliott" <Simon at ctsn.co.uk> wrote in message news:45105819$1 (AT) newsgroups (DOT) borland.com... Quote: I've reduced the app to a small consolde mode test app, and still happens. How small is the test app? Is it small enough that you can post the code here? Is it small enough that you can post it to the attachments newsgroup? Quote: Any thougths? What's the best way to go about tracking this down? Whenever problems like this occur the best thing to do is either reduce code until the problem goes away or start from scratch and add code until the problem exhibits itself. I can confirm that I have seen access violations that happen in release mode that do not happen in debug mode; however, it's not been specific to ADO. Does your code have any startup initializers that rely on other startup initializers? Does your project rely on other packages or libraries that you have created or other third party packages or libraries? Is your project a standalone EXE? Hopefully I have asked enough questions to get this ball rolling. - Clayton Back to top Simon Elliott Guest Posted: Sat Sep 23, 2006 8:48 pm    Post subject: Re: Strange ADO issue doesn't happen in debug mode On 23/09/2006, Clayton Arends wrote: Quote: How small is the test app? Is it small enough that you can post the code here? Is it small enough that you can post it to the attachments newsgroup? I've reduced it to a very small app: see below. Quote: Any thougths? What's the best way to go about tracking this down? Whenever problems like this occur the best thing to do is either reduce code until the problem goes away or start from scratch and add code until the problem exhibits itself. I can confirm that I have seen access violations that happen in release mode that do not happen in debug mode; however, it's not been specific to ADO. Does your code have any startup initializers that rely on other startup initializers? Does your project rely on other packages or libraries that you have created or other third party packages or libraries? Is your project a standalone EXE? Hopefully I have asked enough questions to get this ball rolling. Yes, thanks for getting this started: I had just about run out of ideas. The code follows. It's just a very basic console mode app created by the BCB6 console wizard. Works fine in debug mode and fails with a memory overwrite exception in release mode. //------------------------------------------------------------------- #include <vcl.h> #include <ADODB.hpp> #include <DB.hpp> #pragma hdrstop //------------------------------------------------------------------- #pragma argsused int main(int argc, char* argv[]) { CoInitializeEx(NULL, COINIT_MULTITHREADED); AnsiString strDatabaseName = "E:\\Work\\AntennaAudio\\Datalogger\\dev\\tmdb6X.mdb"; AnsiString strConnectionString; AnsiString strSQL; Variant vCatalog; Variant vConnection; // Connection string. Use 4.0 to make an Access 2000 object strConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="; strConnectionString += strDatabaseName; // Create the database vCatalog=Variant::CreateObject("ADOX.Catalog"); vCatalog.Exec(Function("Create") << strConnectionString); vConnection = vCatalog.Exec(PropertyGet("ActiveConnection")); vCatalog.Clear(); // Create the tables strSQL = "CREATE TABLE tblTest (MyIndex COUNTER(1,1) NOT NULL CONSTRAINT PrimKey PRIMARY KEY, MySerial INTEGER, MyShort SHORT, MyTimen DATETIME, MyText TEXT(255), MyInteger INTEGER, MyByte BYTE)"; vConnection.Exec(Function("Execute") << strSQL); // Close the database vConnection.Exec(Function("Close")); vConnection.Clear(); CoUninitialize(); return 0; } Back to top Clayton Arends Guest Posted: Sun Sep 24, 2006 12:26 am    Post subject: Re: Strange ADO issue doesn't happen in debug mode This will take some investigating to track down. I see exactly what you are talking about. However, one thing I'd like to mention is that this problem might have nothing to do with ADO. Your code doesn't use the ADO classes (TADOConnection, etc) or the ADO COM objects (Adoint::_Connection, etc). Instead it uses what I will call the VB way of accessing COM objects through Variant. I have no experience with this. Though, from what I see it doesn't look like anything is wrong with your code. - Clayton Back to top Clayton Arends Guest Posted: Sun Sep 24, 2006 12:47 am    Post subject: Re: Strange ADO issue doesn't happen in debug mode The only function that causes the AV in this test application is the "Create" function. If I make no other changes to the application and simply wrap the Exec() call in a try..catch block then the app executes correctly. It even executes other code in the try area which means it's not throwing anything. Example: // Create the database vCatalog=Variant::CreateObject("ADOX.Catalog"); try { vCatalog.Exec(Function("Create") << strConnectionString); printf("1\n"); //<-- this prints } catch (...) { printf("ouch!\n"); //<-- does not print throw; } printf("2\n"); I don't believe this is the solution but it is interesting. I'm going to perform some more searches in Google. - Clayton Back to top Simon Elliott Guest Posted: Sun Sep 24, 2006 3:03 am    Post subject: Re: Strange ADO issue doesn't happen in debug mode On 23/09/2006, Clayton Arends wrote: Quote: The only function that causes the AV in this test application is the "Create" function. If I make no other changes to the application and simply wrap the Exec() call in a try..catch block then the app executes correctly. It even executes other code in the try area which means it's not throwing anything. Example: // Create the database vCatalog=Variant::CreateObject("ADOX.Catalog"); try { vCatalog.Exec(Function("Create") << strConnectionString); printf("1\n"); //<-- this prints } catch (...) { printf("ouch!\n"); //<-- does not print throw; } printf("2\n"); I don't believe this is the solution but it is interesting. I'm going to perform some more searches in Google. Thanks for looking into this. I agreee that this is not the solution, but hopefully it's iterating toward a solution. You mentioned in an earlier post that this is more a "VB" solution. I was advised when starting out on this, that this was closer to the underlying "bare metal" of the way that MS Windows handles ADO, and therefore I'd experienece less problems and issues. Is this perhaps not the case? I wonder if my prerequistes for mulithreading CoInitializeEx(NULL, COINIT_MULTITHREADED); is incorrect. The app which ultimately uses all of this is heavily multithreaded so I want to make sure that mulithreading support is enabled. -- Simon Elliott http://www.ctsn.co.uk Back to top Clayton Arends Guest Posted: Sun Sep 24, 2006 3:33 am    Post subject: Re: Strange ADO issue doesn't happen in debug mode "Simon Elliott" <Simon at ctsn.co.uk> wrote in message news:4515af1d (AT) newsgroups (DOT) borland.com... Quote: Thanks for looking into this. I agreee that this is not the solution, but hopefully it's iterating toward a solution. I was only able to find one post that demonstrates similar behavior. I searched Google for "cppbuilder variant exec debug av" and this is the link (one line, of course): http://groups.google.com/group/borland.public.cppbuilder.activex/ msg/6252a8bcadff64c4?dmode=source Quote: You mentioned in an earlier post that this is more a "VB" solution. I was advised when starting out on this, that this was closer to the underlying "bare metal" of the way that MS Windows handles ADO, and therefore I'd experienece less problems and issues. Is this perhaps not the case? I don't know if it's more/less optimal than using the VCL classes found in ADODB or using the COM classes in ADOINT. I'm sure there are some hidden features that are much easier to get at using the technique you are using. The "VB way" is definitely more flexible since you can access any OLE/COM interface without making a class or importing a DLL or other LIB and header. However, I doubt that you will be able to use TDataSource or the other DB components/controls through this Variant interface (I'm prepared to eat those words if someone else can contradict me). If this is not a requirement for you then this won't be an issue. I'm afraid that at this point my information on this problem is maxed out and with it my ability to help "fix" it. For now you may have to leave your app in "debug" mode. I have one released product that we had to do that. There was no time to hunt for the cause of an infrequent error we were experiencing in debug mode. Fortunately, this only adds about 2K to the application so is not really a big deal. Perhaps you can contact Wayne Smith and ask him if he was ever successful in finding his problem. - Clayton Back to top Simon Elliott Guest Posted: Wed Sep 27, 2006 1:34 am    Post subject: Re: Strange ADO issue doesn't happen in debug mode On 23/09/2006, Clayton Arends wrote: Quote: I don't know if it's more/less optimal than using the VCL classes found in ADODB or using the COM classes in ADOINT. I'm sure there are some hidden features that are much easier to get at using the technique you are using. The "VB way" is definitely more flexible since you can access any OLE/COM interface without making a class or importing a DLL or other LIB and header. However, I doubt that you will be able to use TDataSource or the other DB components/controls through this Variant interface (I'm prepared to eat those words if someone else can contradict me). If this is not a requirement for you then this won't be an issue. I'm afraid that at this point my information on this problem is maxed out and with it my ability to help "fix" it. For now you may have to leave your app in "debug" mode. I have one released product that we had to do that. There was no time to hunt for the cause of an infrequent error we were experiencing in debug mode. Fortunately, this only adds about 2K to the application so is not really a big deal. Perhaps you can contact Wayne Smith and ask him if he was ever successful in finding his problem. That might be the way forward. 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