Add an early out to gpr_cpu_test

This test consumes a huge amount of CPU. On Windows, it additionally starves other tests from getting scheduled - for long enough that those tests time out and fail.
Historically tests starting shortly after this test are the most likely to fail.

Once we've seen all CPU's, we will no longer do anything useful - so check for that, and finish up early whenever possible.

1 files changed, 7 insertions, 1 deletions

diff --git a/test/core/support/cpu_test.c b/test/core/support/cpu_test.c
index fa83878a15..138ad6a19e 100644
--- a/test/core/support/cpu_test.c
+++ b/test/core/support/cpu_test.c
@@ -80,7 +80,7 @@ static void worker_thread(void *arg) {
   struct cpu_test *ct = (struct cpu_test *)arg;
   gpr_uint32 cpu;
   int r = 12345678;
-  int i, j;
+  unsigned i, j;
   for (i = 0; i < 1000 / GRPC_TEST_SLOWDOWN_FACTOR; i++) {
     /* run for a bit - just calculate something random. */
     for (j = 0; j < 1000000 / GRPC_TEST_SLOWDOWN_FACTOR; j++) {
@@ -90,7 +90,13 @@ static void worker_thread(void *arg) {
     GPR_ASSERT(cpu < ct->ncores);
     gpr_mu_lock(&ct->mu);
     ct->used[cpu] = 1;
+    for (j = 0; j < ct->ncores; j++) {
+      if (!ct->used[j]) break;
+    }
     gpr_mu_unlock(&ct->mu);
+    if (j == ct->ncores) {
+      break; /* all cpus have been used - no further use in running this test */
+    }
   }
   gpr_mu_lock(&ct->mu);
   ct->r = r; /* make it look like we care about r's value... */