Bug: WinSCP freeze for 5 seconds when get focus back

Hi,

WinSCP periodically freeze for 5 seconds, GUI is not responsible, after while it gets grey shade and mouse cursor is changed to circle. After 5 second everything continues working well.

WinSCP 5.21.3, Windows 10 x64 21H1 19043.1949
problem persist in couple of last versions

Steps to reproduce:

1. Configure use of external editor and open remote file in external editor by double-clicking in WinSCP.
   
2. Edit and save file and terminate external editor.
   
3. When WinSCP get focus back, then it freeze for about 5 seconds. Sometimes get freezed during remote directory browsing also.
   

WinSCP log file with Debug 2 contains repeated generic messages only
silence during freeze

Windows network shares dismounted, antivirus disabled.
Network activity checked with Wireshark, no problem with broken TCP connection nor unresolved DNS entries. No network activity during freeze at all.
WinSCP.exe process activity checked with SysUtils Procmon with silence during freeze.
WinSCP.exe process checked with SysUtils ProcessExplorer, during freeze one thread uses 6 % of CPU, so it actually doing something.

Same WinSCP version installed in fresh VMWare Workstation virtual machine same Windows version and there is working well, with same network connection.

It seems that WinSCP is doing some kind of refresh after got focus back and it takes long time at some platforms.

Best Regards
Fox

I found than WinSCP.exe is completely pointlessly periodically traversing the local directory C:\ and is finding "something" in directories. This happens periodically and it freezes GUI and it prevent normal operation for couple of second. This happens with 100 % probability when WinSCP GUI get back focus after some other application is closed.

Pattern of this behaviour:

• Searching is based on some magic in directory name. It seems it is searching for directory with numbers in name, like 0001.
  
• If directory with magic is found, then subdirectories is searched. Recursively.
  
• After searching, the results are processed and if there are a lot of findings, GUI is freezed for couple seconds.
  

How to reproduce this bug:

• Create thousands of directories with C:\NNNN pattern, from C:\0000 to C:\9999
  
• Fill these directories with many regular files, so that there are really many files.
  
• In the WinSCP try edit and save remote file over SSH, close editor and click to WinSCP.
  

Thanks for your detailed report!
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

I have added this bug to the tracker:
Issue 2114 – Stall when new folder is detected and the drive contains folders with numerical names