bug(developer): starting multiple instances of TIKE simultaneously causes `EFOpenError`

[sentry-io[bot]]

Sentry Issue: KEYMAN-DEVELOPER-1PR

OS Version: Windows 10.0.19045 (4291)
Report Version: 104

Application Specific Information:
Exception EFOpenError in module tike.exe at 000797B7.
Cannot open file "C:\Users\AHSN LAPTOP\Documents\Keyman Developer\Projects\kuswa_s_keyboard\kuswa_s_keyboard.kpj". The process cannot access the file because it is being used by another process.

Thread 0
0   tike.exe                        0x4797b7            System.Classes.TFileStream.Create (System.Classes.pas:9208)
1   tike.exe                        0x47966c            System.Classes.TFileStream.Create (System.Classes.pas:9178)
2   tike.exe                        0x73845f            Keyman.Developer.System.Project.ProjectFile.TProject.Load (Keyman.Developer.System.Project.ProjectFile.pas:844)
3   tike.exe                        0xe99321            Keyman.Developer.UI.Project.ProjectFileUI.TProjectUI.Load (Keyman.Developer.UI.Project.ProjectFileUI.pas:164)
4   tike.exe                        0x7380bd            Keyman.Developer.System.Project.ProjectFile.TProject.Create (Keyman.Developer.System.Project.ProjectFile.pas:782)
5   tike.exe                        0xe9914d            Keyman.Developer.UI.Project.ProjectFileUI.TProjectUI.Create (Keyman.Developer.UI.Project.ProjectFileUI.pas:137)
6   tike.exe                        0x8fef95            Keyman.Developer.UI.Project.ProjectUI.LoadGlobalProjectUI (Keyman.Developer.UI.Project.ProjectUI.pas:96)
7   tike.exe                        0xe9264f            UfrmMain.TfrmKeymanDeveloper.FormCreate (UfrmMain.pas:597)
8   tike.exe                        0x7c326f            JvDockControlForm.TJvDockBaseControl.DoFormOnCreate (JvDockControlForm.pas:2378)
9   tike.exe                        0x679ace            Vcl.Forms.TCustomForm.AfterConstruction (Vcl.Forms.pas:3722)
10  tike.exe                        0x679a7f            Vcl.Forms.TCustomForm.Create (Vcl.Forms.pas:3712)
11  tike.exe                        0x685110            Vcl.Forms.TApplication.CreateForm (Vcl.Forms.pas:10866)
12  tike.exe                        0xe9ca69            Keyman.Developer.System.Main.RunWithExceptionsHandled (Keyman.Developer.System.Main.pas:73)
13  tike.exe                        0xe9c8f2            Keyman.Developer.System.Main.RunKeymanDeveloper (Keyman.Developer.System.Main.pas:43)
14  tike.exe                        0xeb5388            tike.tike
15  KERNEL32.DLL                    0x7755fcc8          BaseThreadInitThunk
16  ntdll.dll                       0x77d07c5d          _RtlUserThreadStart
17  ntdll.dll                       0x77d07c2d          _RtlUserThreadStart

17.0.325

[mcdurdin]

I was able to replicate this by running tike && tike at the command line -- indicating a race when two instances both try to load the project at the same time

[mcdurdin]

This may require some rearchitecture of the TMultiProcessCoordinator to remove its dependency on window enumeration, because we enumerate the running processes before we create the main window, which means two processes may each independently do the window enumeration, find no windows, and both end up becoming the 'first' process, attempting to load the last open project.

Or we could always create the window before calling the enumeration? (This may have other side-effects to consider.)

Or as a stop-gap, we could fall back to a null-project scenario in the case of file lock, which would reduce the incidence of this.