I have a program that extracts text from PDFs. It runs as a scheduled task on Windows Server 2008.
The library I use is ByteScout's PDF Extractor SDK, which is based on Tesseract under the covers.
Since it went live last November, the program has successfully extracted text from over 50,000 PDFs from many different sources.
It recently hung on a single PDF and subsequently on a second one, from the same source in the same visual format.
I am able to recreate the problem using a trivial 12 line program. I sent this program to the vendor but running that program in their environment works (it does not hang).
So I did some experimentation and this is where it gets strange.
The program works on my PC (Windows 7) if I RDP to it, but not if I am directly logged in. This behavior is repeated on other Windows 7 PCs in our environment.
It works on Server 2008 if I am RDPed, but not as a scheduled task.
It works on Windows 10, whether I am RDPed or logged in directly.
If I watch the program in Process Monitor when it is stuck, I can see that it is opening and reading C:\Windows\Fonts\times.ttf over and over again.
If it was only working using RDP, I'd wonder if the cause had anything to do with failing use of graphics acceleration or some such, but given that it doesn't work as a scheduled task where none would be present either, I think that's a blind alley.
Does anyone have any suggestions where to look next?
So ByteScout have fixed the problem. To quote Eugene on the cause ...
The problem is in System.Drawing and GDI+. Sometimes it crashes on text drawing operations that are normal in PDF but causing some internal exceptions in System.Drawing. Moreover, it's behavior varies depending on display device capabilities. That is why it works in RDP session and crashes on a desktop.
We are trying various workarounds on these crashes, attempting to fall back to alternate text drawing ways. The hanging is related to these fallbacks.
Related
I have a VB6 application that I provide support for. This application works on both Windows XP and Windows 7. Some users were migrated from Windows XP to Windows 7 using the User State Migration tool. These users now receive a generic "Application has crashed" Windows error message when they open certain screens (forms) in the application. My assumption is that there is a missing dll/ocx reference, but I'm having trouble tracking it down.
I've tried many/varied troubleshooting techniques:
Full uninstall and reinstall of my application
Manually re-registering all dll's and ocx's that I know are used
Running Process Monitor on a broken computer and a working computer to compare what dll's and ocx's are accessed. The answer might be here but even after filtering out most of the background noise the amount of data is overwhelming. At a minimum I reviewed all of the calls right before it crashes and all of the calls that were not successful. All of the non-successful calls match between working and non-working.
Installed the Windows Debugger Tools and captured a crash dump. Analyzed the crash dump with DebugDiag. DebugDiag says the exception is in msvbvm60.dll. I tried building a PDB file for my exe and loading it in DebugDiag to get more detail about where the exception is occuring but DebugDiag doesn't want to accept the PDB (might be doing something wrong here, but it just seems to ignore it. This same PDB file works fine when I do remote debugging, however.)
I recompiled my VB6 program without any optimizations in PCode. I've read online that sometimes building in PCode, while bad for performance, will tell you the real exception.
Used the above created PDB file to remote debug the VB6 application. The debugger says that the application crashes after the new window has been created, on a line that sets MousePointer = vbHourGlass... To me it seems unlikely that this is the real cause of the error. There are at least 20 other locations in the program where this same line is called and all work fine.
(Forgot about this one)
Used Dependency Walker and profiled the application on both a working and non-working computer. All errors found by dependency walker were the same between the two computers. There were no additional dependencies found on a working computer, and all missing dependencies on the non-working computer were also missing on the working one.
None of these actions changed my error message or showed me what the error is (unless it really is the mouse cursor issue)... There are no entries in the Windows Event Log related to the app crash.
The non-working and working computers all have the same base Windows 7 image, the only difference is whatever is being changed by USMT, which further convinces me that this is some kind of quirky configuration change or a missing dll/ocx or perhaps an unregistered dll/ocx.
Any ideas or thoughts on how I can track down the root cause of the issue would be greatly appreciated.
Update 1 - Response to questions
#MarkHall I have tried running it as admin, though not with UAC off. The application runs fine on a Windows 7 box as a non-admin with full UAC. Windows XP was 32-bit, Windows 7 is 64-bit, but again it works just fine on a like for like box where the user was not migrated from Windows XP.
#Beaner It's possible that it stores settings somewhere that have been corrupted, but the remote debugging leads me to think that it's more likely something else since it seems to die on a step related to the UI, which then makes me think it's probably a missing dll/ocx reference.
#Bob77 The application is installed into Program Files (x86). While many of the libraries do reside in the same folder, they are all registered.
Peter, often I've noticed that the debugger will indicate a line of code that is actually incorrect, depending on WHERE in the actual assembly language the fault occurs. You should look REAL close around your statement that sets the cursor to vbHourGlass. Your exception is PROBABLY happening BEFORE that line of code, but that line is what the debugger thinks is the actual faulted line of code.
Since you said it happens when a window OPENS, I'd look real close at any ocx's you may have referenced on the form, but perhaps NOT actually being used, or called. You might have one there that you don't intend to be there, that could be causing security issues, or something on Win7? Edit the .frm file by hand if you have to, and look at all the GUIDs the form references.
It is possible that one machine is using PER-USER registration, and the other is using PER-SYSTEM registration?? I don't know...
I would take a much closer look at the form that you are trying to open, and be VERY cautious of everything you are doing in the form load events, and so on. This sounds like it could be something as stupid as Windows Aero being enabled on one system, and not another, or some other sort of "Theme" setting that is throwing the VB Form Rendering routine into a hissyfit... Perhaps even something as stupid as a transparent color index in the icon you selected for that from?
If you are still developing this app, (or at least maintaining it), create an entirely NEW form, and re-create all the controls, etc, on the form (resist the temptation to copy/paste them from the old one...), and then see if THAT does the trick. Then, copy all the event code to the new form one event at a time, with at LEAST enough event code to make the form function, even if it's just a "dead form", that loads no data, or whatever the form is supposed to do. Check and debug after each change, and you WILL find it eventually. Of course, make sure you isolate one of the defunct systems to have a platform that you can duplicate the issue on, or then it's just guessing. I find that using something like Acronis w/ Universal Restore is a great option to then take the image file into a good HV, like VirtualBox, and then restore that image as a VM, so you can debug without interfering with your actual users. This sounds like a lot of work, but then again, so is re-writing an application that already exists, right? :)
Failing THAT... /* and */ are your friends!! (Well, we're dealing with VB, so ' would be your best friend! heh... But I'd start commenting out all the code on the form until that sucker opens. Then once it opens, start putting one line back at a time, and re-running it... That's called "VooDoo Debugging", but sometimes, you gotta do what you gotta do...
THANKS A LOT PETER! :) Now you got ME so involved in this, I feel like I'M the one debugging this sucker! Like if it was MY code I was trying to fix! :)
Let me know if any of this helps... I am actually quite interested in what you discover.
I have a completely random error popping up on a particular piece of software out in the field. The application is a game written in VB6 and is running on Windows 7 64-bit. Every once in a while, the app crashes, with a generic "program.exe has stopped responding" message box. This game can run fine for days on end until this message appears, or within a matter of hours. No exception is being thrown.
We run this app in Windows 2000 compatibility mode (this was its original OS), with visual themes disabled, and as an administrator. The app itself is purposely simple in terms of using external components and API calls.
References:
Visual Basic for Applications
Visual Basic runtime objects and procedures
Visual Basic objects and procedures
OLE Automation
Microsoft DAO 3.51 Object Library
Microsoft Data Formatting Object Library
Components:
Microsoft Comm Control 6.0
Microsoft Windows Common Controls 6.0 (SP6)
Resizer XT
As you can see, these are pretty straightforward, Microsoft-standard tools, for the most part. The database components exist to interact with an Access database used for bookkeeping, and the Resizer XT was inserted to move this game more easily from its original 800x600 resolution to 1920x1080.
There is no networking enabled on the kiosks; no network drivers, and hence no connections to remote databases. Everything is encapsulated in a single box.
In the Windows Application event log, when this happens, there is an Event ID 1000 faulting a seemingly random module -- so far, either ntdll.dll or lpk.dll. In terms of API calls, I don't see any from ntdll.dll. We are using kernel32, user32, and winmm, for various file system and sound functions. I can't reproduce as it is completely random, so I don't even know where to start troubleshooting. Any ideas?
EDIT: A little more info. I've tried several different versions of Dependency Walker, at the suggestion of some other developers, and the latest version shows that I am missing IESHIMS.dll and GRPSVC.dll (these two seems to be well-known bugs in Depends.exe), and that I have missing symbols in COMCTRL32.dll and IEFRAME.dll. Any clues there?
The message from the application event log isn't that useful - what you need is a post mortem process dump from your process - so you can see where in your code things started going wrong.
Every time I've seen one of these problems it generally comes down to a bad API parameter rather than something more exotic, this may be caused by bad data coming in, but usually it's a good ol fashioned bug that causes the problem.
As you've probably figured already this isn't going to be easy to debug; ideally you'd have a repeatable failure case to debug, instead of relying on capturing dump files from a remote machine, but until you can make it repeatable remote dumps are the only way forwards.
Dr Watson used to do this, but is no longer shipped, so the alternatives are:
How to use the Userdump.exe tool to create a dump file
Sysinternals ProcDump
Collecting User-Mode dumps
What you need to get is a minidump, these contain the important parts of the process space, excluding standard modules (e.g. Kernel32.dll) - and replacing the dump with a version number.
There are instructions for Automatically Capturing a Dump When a Process Crashes - which uses cdb.exe shipped with the debugging tools, however the crucial item is the registry key \\HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\AeDebug
You can change your code to add better error handling - especially useful if you can narrow down the cause to a few procedures and use the techniques described in Using symbolic debug information to locate a program crash. to directly process the map files.
Once you've got a minidump and the symbol files WinDbg is the tool of choice for digging into these dumps - however it can be a bit of a voyage to discover what the cause is.
The only other thing I'd consider, and this depends on your application structure, is to attempt to capture all input events for replay.
Another option is to find a copy of VMWare 7.1 which has replay debugging and use that as the first step in capturing a reproducible set of steps.
Right click your executable object and let it be WINXP compatible pending
when you discover source of the problem to finally solve it
I am trying to write a non-interactive process that prints PDFs, and I need advice on how to build this on Windows Server 2008 (and Vista/7).
Previously, we have had a scheduled task (set to run whether the user account was logged on or not) that would print all PDFs inside of a directory. (A seperate process would move the PDFs into the directory.) At runtime, this would spin up another process (either Adobe Reader or Foxit Reader) to print the PDF. Both Adobe Reader and Foxit Reader feature silent printing, so everything would be sent to the default printer for the user that the scheduled task ran as. No UI was ever generated, and all files would be printed without a hitch. This worked on Server 2003.
The process no longer works on Server 2008. I'm not entirely sure, but I believe this has to do with Session 0 Isolation. I cannot prove this. However, I can say that the process works as a scheduled task when set as "Run only when the user is logged in". Now, while this works, it forces a user to log in to the machine, and thus does not fulfill my requirements. (My first clue was in this previous question.)
I cannot determine how I can move forward on this. Is there any way to fulfill my requirements?
A few notes :
Every solution I've seen seems to be using the credentials of a logged-in user. See the question I linked above - the solution listed appears to be grabbing the token of a logged-in user and using it to run the program. (Look at the GetCurrentUserToken() procedure - the returned value is later used in the API call CreateProcessAsUser().)
My current process generates, as near as I can tell, no UI. I've verified, using ProcMon, that the reader process (Adobe or Foxit) appears to print correctly and the print driver itself appears to have a problem. This is backed up by an attempt to use a print-to-file driver - the print-to-file driver runs in three visible steps and clearly finishes the first for all files without starting the second. So how does Session 0 Isolation affect the printer driver? This is unclear to me. (The best documentation I can find on the subject only mentions that printer drivers may be affected, even though the print spooler runs in Session 0.)
Printing as a Windows service never works, even when the process has 'Allow service to interact with desktop' checked.
Bold text added to counter the blear-inducing wall-of-text effect.
Try using Foxit Reader instead of Acrobat-Reader.
Foxit Reader supports GUI-less / commandline execution properly, also in Windows 2008 and above!
Printing is also possible, but you will have to add (or check) the printer in session0 every time you run the printjob.
If you need any more help on that, just ask again. I already built a powershell script which runs in task scheduler to print pdf-files with help of Foxit Reader.
I have a program that I run on multiple network PCs. When I compiled the most recent version, it runs extremely slowly on 2 PCs on the network, but runs fine for everyone else.
This used to happen with my old dev PC when I had an additional 2gb RAM installed. When I would remove the additional 2gb and recompile, it would then work fine for everyone.
Now, I am on a completely new machine and am having the same issue. I've tried to rebuild the project after rebooting, but still have the same issue.
For all other PCs, the program loads in about 3-5 seconds. On these 2 PCs, it takes anywhere from 45 seconds to 1.5 mins to load...
One of the PCs is an older Dell Dimension 8200, but the other is a newer OptiPlex that is identical to several other PCs on the network, so this is what is really making it so confusing.
For now, I've had to revert to the old version so it will run correctly for everyone.
Does anyone have any idea of anything to try?
Thanks in advance!!!
Edit:
Ok, it was an exhausting day yesterday trying various things to solve this issue. Here is what I tried and where the problem begins:
Using the new program
Went back to old versions of all updated components, but still had the same issue
Using the old program
I decided to go back to the drawing board and start from the old version of the application and incrementally add the new features a small piece at a time.
Recompiled the old version using the old components - program works fine
Updated to new DevExpress components - program works fine
Updated to new ESBPCS components - program works fine
Updated to new DeepSoftware components - program works fine
Ok, so now we know there is nothing with the component sets I've updated...
Added 1 image to each of 2 image lists - program works fine
Added new database table - program works fine
Added code to open and close the new table - program works fine
Added new action to action list and added a menu item and toolbar button to new action (action does nothing at this point) - program works fine
Added a new BLANK form to the application and added code to open the new form - BAM!!!
So, adding just one form to the application is what's causing the issue! I removed all the code for the opening of the form, commented out the uses clauses and removed the uses entry from the project source and everything is back to normal!
Anybody have any idea about this?
Thanks!
Edit 2:
For #Warren P - here is my .DPR source:
program Scheduler;
uses
ExceptionLog,
Forms,
SchedulerMainUnit in 'SchedulerMainUnit.pas' {FrmMain},
SchedulerDBInfoUnit in 'SchedulerDBInfoUnit.pas' {FrmDBInfo},
SchedulerHistoryUnit in 'SchedulerHistoryUnit.pas' {FrmHistory},
SchedulerOptionsUnit in 'SchedulerOptionsUnit.pas' {FrmOptions},
SchedulerExtVersionUnit in 'SchedulerExtVersionUnit.pas' {FrmExtVersion},
SchedulerSplashUnit in 'SchedulerSplashUnit.pas' {FrmSplash},
SchedulerInfoUnit in 'SchedulerInfoUnit.pas' {FrmInfo},
SchedulerShippedUnit in 'SchedulerShippedUnit.pas' {FrmShipped}; {<-- This is the new form with the issue}
{$R *.res}
begin
Application.Initialize;
Application.Title := 'SmartWool WIP Scheduling Assistant';
Application.CreateForm(TFrmMain, FrmMain);
Application.CreateForm(TFrmDBInfo, FrmDBInfo);
Application.CreateForm(TFrmHistory, FrmHistory);
Application.CreateForm(TFrmOptions, FrmOptions);
Application.CreateForm(TFrmExtVersion, FrmExtVersion);
Application.Run;
end.
And here is the intialization section of the main form to create the splash:
initialization
FrmSplash:=TFrmSplash.Create(Application);
FrmSplash.Show;
FrmSplash.Refresh;
Edit 3:
Anybody??? Please?
It could be that the program is waiting for timeouts when trying to access resources that are not available on that machine such as network drives or Internet hosts.
Try running Process Monitor when starting up your program and look for file open calls. Filter the output so it only shows your process.
http://technet.microsoft.com/en-us/sysinternals/bb896645
Performance problems initially can seem very daunting at first.
I have been on many teams where people have tried to guess at a reason for performance problems. This sometimes works, but is far less effective than actually measuring the code.
When reproducible on a development machine, I would recommend a profiler.
There was a previous question that asked about
Delphi Profiling tools which has several possible tools you could use.
When you can't reproduce the problem on your development machine, then it becomes a bit more difficult, but not impossible. Typically I have found that problems are related to an application dependency that is different, and not performing well. Understanding the external influences on your application can help pinpoint the problem.
Specifically common external problems in some of my applications.
Network
Database
Application Servers
Installation or Data File Location (i.e. Disk Performance)
Virus and Malware Scanners
Other application interring with yours such as a virus.
To monitor for items related to the network (i.e. Database, web services, etc...)
I typically use Wireshark which allows me to see if resources are responding in expected times. My most common problem is poor performing DNS and can found using Wireshark.
You can use the AutoRuns program to determine everything that starts up when your computer does, it's useful in determine differences between machines.
But most of all I have logging that can be turned on in my applications and this allows me to isolate the problem to a specific area of code. This narrowing down to a specific section of code reduces the guessing, and allows you to focus on a few possible problems.
I created a log function for this that I call at specific places (in your case especially during startup). It adds a timestamp to each log text and stores them in a TMemo that is regularly saved. Not only very helpful when debugging, but may also shed some light on your problem.
Are you using code signing - ie Microsoft Authenticode? If so, then outdated certificate authorities on the computers can cause significant delays to startup.
First, I would try to defragment the hard disk. If still slow, I would check the power supply. Maybe your hard disk are getting insufficient energy.
Check if there is the same antivirus software on those 2 problematic computers. If so, then your Delphi application may match byte pattern used in some virus made in Delphi. Update virus definitions to solve it, or report false alarm to antivirus company, or change antivirus software.
Check if there isn't any printer installed on those 2 problematic computers. If it is so, then add any printer and try again.
Idea 1:
One reason I have seen for very slow application load time, is when printing or reporting system components like Developer Express Express Print, are in your application.
The problem I saw when using Developer Express Printing components, is that I had an offline or non-responsive network printer in my list of printers (check the control panel printer icon) that was not responding. Some of those Developer Express components seem to read some information from each printer you have installed, and the solution was to go to those clients, and delete old printers from their control panel, that were no longer being used. Each not-responding network printer added up to 60 seconds for a TCP Timeout, to the startup time of my application.
Update - Idea 2:
Download MS DebugView and install it on the machine that runs slowly. Now go back to your main development PC, open the IDE, open your main project file (right click on the project, view project source in project viewer), this will show you the contents of your main project source file (.dpr). go to the main begin....end. block. Now set a breakpoint on the main begin statement, and single step INTO (not OVER) and you will see all the module initialization sections. In each one add this: OutputDebugString('ModuleName').
Now when you run this inside the Delphi Ide you will see messages, and see how far apart they come in, and understand what is taking a long time to initialize. Instead of installing the delphi ide onto the machine that runs slowly, Debug View (which is less than 400kb single executable) will be run, and it will show you these debug messages, along with a nice time display (##.# seconds) for each message.
MS Debug view is here.
Are you allowing the forms to be constructed on initialization within the DPR source? If so, you may do well to consider whether or not you want those forms sucking up memory the entire time, more-over if you want those forms to be wasting the application's time on load.
A rule of thumb: If the form is used a LOT during the application's execution, allow it to be constructed when the application loads (this will work out faster over-all than constructing the instance "on-demand").
If the form is not used very often at all (for example, a Dialog or an About Box), delete the "Application.CreateForm" line from the DPR source, and instead construct your instance on request...
var
LForm: TfrmAbout;
begin
Application.CreateForm(LForm, TfrmAbout);
try
LForm.ShowModal;
finally
LForm.Free;
end;
end;
Now that form (which may not even be displayed during the program's execution) is not sucking up system resources, and will not slow down the application's load time.
It may not solve your problem 100%, but it should certainly help!
I have a console application (written in VB6 ) which is behaving strangely on my machine. I kick it off from the command line and what should be a two minute job drops straight back to the prompt - if I run this on another machine the executable will sit and wait until the job finishes before returning control back to the prompt. If I check process explorer I can see that the executable is running as a background process and other than this strange background-ness is running as expected.
Any thoughts on why this could be happening? (Running on 32-bit Windows XP Pro SP3.)
It's totally unclear whether this is an application you wrote and have the source code for. If that's the case, you need to get in and start debugging. At the least, use OutputDebugString to send information about what's going on to any number of potential viewers. Taking that a step further, consider rewiring the app using the Console module I wrote, along with vbAdvance to recompile. This combination will allow you the full power of the VB6 IDE to debug within. No more guessing about what's going on.
Then again, if it's not your app, I'm not sure what VB6 has to do with it and wish you the best of luck trying to figure out what's up.
It sounds to me as though the app isn't being recognised as a console app on one of your machines. Console apps weren't officially supported in VB6, although there are some well-known hacks for creating them (particularly the free add-in vbAdvance). Possibly your console app is a bit unreliable? If Windows thinks your app is a GUI rather than a console app, it won't wait for it to finish.
As a pragmatic workaround: try launching with start /wait rather than just using the exename. That forces the command prompt to wait for the program to finish, whether it's a GUI app or a console app.
Sounds like an error is occurring that is being 'swallowed' by the application. Do you have the source code?
Errors in VB6 apps are often due to some COM component not installed and/or registered.
Download SysInternals Process Monitor and this will show up accesses to ProgIDs that fail (uninstalled/unregistered COM components).
Check out: Process Monitor - Hands-On Labs and Examples.
Have you checked permissions? Is the application accessing any network based resources?