The error “double free or corruption (fasttop)” in multithread

After finishing a application in multithread mode, when existing the application, the error occured:

Graphics systems deleted.
Visualization Manager deleting…
double free or corruption (fasttop)
double free or corruption (fasttop)

but when using only one thread, everything worked well.
so what causes this error?

_Geant4 Version:_11.2.0
_Operating System:_Ubuntu 20.04
_Compiler/Version:_GCC 9.4.0
_CMake Version:_3.16.3

It’s impossible to know what’s causing that error with only that information. The best approach will be to run the program through a debugger like gdb as it should be able to produce a backtrace of any error/segfault, or breakpoints can be put in and then stepping used to proceed the program line by line to track down where these errors are produced.

@bmorgan , thank you, i will try!