Update MP UT to support arbitrary # of GPUs; multiple bugfixes (#16)

* Fixing temp file creation/deletion for Clique kernel mode.

* Refactoring of MP unit tests; include bugfixes and general support for any number of GPUs

* GroupCall MP UT properly quits when too many devices specified

* MP UT will programmatically set NCCL_COMM_ID if not specified; updated install script

test/test_GatherMultiProcess.cpp

@@ -10,63 +10,27 @@ namespace CorrectnessTests
 {
     TEST_P(GatherMultiProcessCorrectnessTest, Correctness)
     {
-        Dataset* dataset = (Dataset*)mmap(NULL, sizeof(Dataset), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
         dataset->InitializeRootProcess(numDevices, numElements, dataType, inPlace, ncclCollGather);
-        Barrier::ClearShmFiles(std::atoi(getenv("NCCL_COMM_ID")));
+        std::vector<int> pids(numDevices);
 
-        int pid1 = 0;
-        int pid2 = 0;
-        int pid3 = 0;
-        pid1 = fork();
-
-        // From this point on, ignore original process as we cannot have it create a HIP context
-        if (pid1 == 0)
+        int gpu = -1;
+        for (int i = 0; i < numDevices; i++)
         {
-            pid2 = fork();
-            if (numDevices > 2)
+            gpu++;
+            int pid = fork();
+            if (pid == 0)
             {
-                pid3 = fork();
-            }
-            if ((pid2 > 0 && pid3 == 0 && numDevices == 2)  || (pid2 > 0 && pid3 > 0 && numDevices > 2))
-            {
-                // Process 0
-                TestGather(0, *dataset);
-                if (pid3 > 0)
-                {
-                    waitpid(pid3, NULL, 0);
-                }
-            }
-            else if ((pid2 == 0 && pid3 == 0 && numDevices == 2) || (pid2 == 0 && pid3 > 0 && numDevices > 2))
-            {
-                // Process 1
-                TestGather(1, *dataset);
-                if (numDevices > 2)
-                {
-                    waitpid(pid3, NULL, 0);
-                }
-                exit(0);
-            }
-            else if (pid2 > 0 && pid3 == 0 && numDevices > 2)
-            {
-                // Process 2 (available when numDevices > 2)
-                TestGather(2, *dataset);
-                exit(0);
-            }
-            else if (pid2 == 0 && pid3 == 0 && numDevices == 4)
-            {
-                // Process 3 (available when numDevices == 4)
-                TestGather(3, *dataset);
-                exit(0);
+                bool pass;
+                TestGather(gpu, *dataset, pass);
+                TerminateChildProcess(pass);
             }
             else
             {
-                exit(0);
+                pids[gpu] = pid;
             }
-            waitpid(pid2, NULL, 0);
-            exit(0);
         }
-        waitpid(pid1, NULL, 0);
-        munmap(dataset, sizeof(Dataset));
+
+        ValidateProcesses(pids);
     }
 
     INSTANTIATE_TEST_SUITE_P(GatherMultiProcessCorrectnessSweep,
@@ -88,7 +52,7 @@ namespace CorrectnessTests
                                 // Number of elements
                                 testing::Values(1024, 1048576),
                                 // Number of devices
-                                testing::Values(2,3,4),
+                                testing::Values(2,3,4,8),
                                 // In-place or not
                                 testing::Values(false),
                                 testing::Values("RCCL_ALLTOALL_KERNEL_DISABLE=0", "RCCL_ALLTOALL_KERNEL_DISABLE=1")),