upload cpp_thread_test

this is a small program that uses C++11 threading to launch a bunch of concurrent BLAS/LAPACK calculations, to test the thread safety of the library

cpp_thread_test/dgemm_thread_safety.cpp

@@ -0,0 +1,104 @@
+#include <iostream>
+#include <vector>
+#include <random>
+#include <future>
+#include "/opt/OpenBLAS_zen_serial/include/cblas.h"
+
+const blasint randomMatSize = 1024; //dimension of the random square matrices used
+const uint32_t numConcurrentThreads = 64; //number of concurrent calls of the functions being tested
+const uint32_t numTestRounds = 32; //number of testing rounds before success exit
+
+inline void pauser(){
+    /// a portable way to pause a program
+    std::string dummy;
+    std::cout << "Press enter to continue...";
+    std::getline(std::cin, dummy);
+}
+
+void launch_cblas_dgemm(double* A, double* B, double* C){
+	cblas_dgemm(CblasColMajor, CblasNoTrans, CblasNoTrans, randomMatSize, randomMatSize, randomMatSize, 1.0, A, randomMatSize, B, randomMatSize, 0.1, C, randomMatSize);
+}
+
+void FillMatrices(std::vector<std::vector<double>>& matBlock, std::mt19937_64& PRNG, std::uniform_real_distribution<double>& rngdist){
+	for(uint32_t i=0; i<3; i++){
+		for(uint32_t j=0; j<(randomMatSize*randomMatSize); j++){
+			matBlock[i][j] = rngdist(PRNG);
+		}
+	}
+	for(uint32_t i=3; i<(numConcurrentThreads*3); i+=3){
+			matBlock[i] = matBlock[0];
+			matBlock[i+1] = matBlock[1];
+			matBlock[i+2] = matBlock[2];
+	}
+}
+
+std::mt19937_64 InitPRNG(){
+	std::random_device rd;
+	std::mt19937_64 PRNG(rd()); //seed PRNG using /dev/urandom or similar OS provided RNG
+	std::uniform_real_distribution<double> rngdist{-1.0, 1.0};
+	//make sure the internal state of the PRNG is properly mixed by generating 10M random numbers
+	//PRNGs often have unreliable distribution uniformity and other statistical properties before their internal state is sufficiently mixed
+	for (uint32_t i=0;i<10000000;i++) rngdist(PRNG);
+	return PRNG;
+}
+
+void PrintMatrices(const std::vector<std::vector<double>>& matBlock){
+	for (uint32_t i=0;i<numConcurrentThreads*3;i++){
+		std::cout<<i<<std::endl;
+		for (uint32_t j=0;j<randomMatSize;j++){
+			for (uint32_t k=0;k<randomMatSize;k++){
+				std::cout<<matBlock[i][j*randomMatSize + k]<<"  ";
+			}
+			std::cout<<std::endl;
+		}
+		std::cout<<std::endl;
+	}
+}
+
+int main(){
+	std::uniform_real_distribution<double> rngdist{-1.0, 1.0};
+	std::vector<std::vector<double>> matBlock(numConcurrentThreads*3);
+	std::vector<std::future<void>> futureBlock(numConcurrentThreads);
+	
+	std::cout<<"Initializing random number generator..."<<std::flush;
+	std::mt19937_64 PRNG = InitPRNG();
+	std::cout<<"done\n";
+	
+	std::cout<<"Preparing to test CBLAS DGEMM thread safety\n";
+	std::cout<<"Allocating matrices..."<<std::flush;
+	for(uint32_t i=0; i<(numConcurrentThreads*3); i++){
+		matBlock[i].resize(randomMatSize*randomMatSize);
+	}
+	std::cout<<"done\n";
+	std::cout<<"Filling matrices with random numbers..."<<std::flush;
+	FillMatrices(matBlock, PRNG, rngdist);
+	//PrintMatrices(matBlock);
+	std::cout<<"done\n";
+	std::cout<<"Testing CBLAS DGEMM thread safety\n";
+	for(uint32_t R=0; R<numTestRounds; R++){
+		std::cout<<"DGEMM round #"<<R<<std::endl;
+		std::cout<<"Launching "<<numConcurrentThreads<<" threads..."<<std::flush;
+		for(uint32_t i=0; i<numConcurrentThreads; i++){
+			futureBlock[i] = std::async(std::launch::async, launch_cblas_dgemm, &matBlock[i*3][0], &matBlock[i*3+1][0], &matBlock[i*3+2][0]);
+			//launch_cblas_dgemm( &matBlock[i][0], &matBlock[i+1][0], &matBlock[i+2][0]);
+		}
+		std::cout<<"done\n";
+		std::cout<<"Waiting for threads to finish..."<<std::flush;
+		for(uint32_t i=0; i<numConcurrentThreads; i++){
+			futureBlock[i].get();
+		}
+		std::cout<<"done\n";
+		//PrintMatrices(matBlock);
+		std::cout<<"Comparing results from different threads..."<<std::flush;
+		for(uint32_t i=3; i<(numConcurrentThreads*3); i+=3){
+			for(uint32_t j=0; j<(randomMatSize*randomMatSize); j++){
+				if (std::abs(matBlock[i+2][j] - matBlock[2][j]) > 1.0E-13){
+					std::cout<<"ERROR: one of the threads returned a different result!"<<i+2<<std::endl;
+					return -1;
+				}
+			}
+		}
+		std::cout<<"OK!"<<std::endl;
+	}
+	return 0;
+}