The OpenCL runtime compiler for the EVMK2H device is not thread safe (it should be --- see Appendix A.2 of the OpenCL 1.1 specification). The following program sometimes crashes randomly with error messages like:
bug: /opt/llvm/llvm33-src/include/llvm/Support/Mutex.h:117: bool llvm::sys::SmartMutex<mt_only>::release() [with bool mt_only = true]: Assertion `((recursive && acquired) || (acquired == 1)) && "Lock not acquired before release!"' failed.
compile with -fopenmp
Thanks, John Romein
#define __CL_ENABLE_EXCEPTIONS
#include <CL/cl.hpp>
#include <iostream>
#include <string>
#include <vector>
const char *kernelSource = "kernel void foo() { }";
void build(cl::Context &context, std::vector<cl::Device> &devices)
{
try { // new thread --> new try/catch block
cl::Program::Sources source(1, std::make_pair(kernelSource, strlen(kernelSource)));
cl::Program program(context, source);
program.build(devices);
} catch (cl::Error &err) {
std::cerr <<"cl::Error(): " << err.what() << '(' << err.err() << ')' << std::endl;
}
}
int main()
{
try
{
cl::Context context(CL_DEVICE_TYPE_ACCELERATOR);
std::vector<cl::Device> devices(context.getInfo<CL_CONTEXT_DEVICES>());
#pragma omp parallel for num_threads(3)
for (int i = 0; i < 20; i ++)
build(context, devices);
} catch (cl::Error &err) {
std::cerr <<"cl::Error(): " << err.what() << '(' << err.err() << ')' << std::endl;
}
return 0;
}
