tree 99d13cf52d7ebcff71330f6d01cf4fa1fcdf929e
parent 79a28d1e49af53f67af7f3387d07e7c9b7339433
author David Gossow <dgossow@google.com> 1472631680 +0200
committer Sameer Agarwal <sameeragarwal@google.com> 1472675144 +0000

Gradient checker multithreading bugfix.

This is a follow-up on c/7470. GradientCheckingCostFunction calls
callback_->SetGradientErrorDetected() in its Evaluate method,
which will run in multiple threads simultaneously when enabling
this option in the solver. Thus, the string append operation
inside that method has to be protected by a mutex.

Change-Id: I314ef1df2be52595370d9af05851bf6da39bb45e