From 055d5aeb7f4362333eb5190e6b35a991a095ea8e Mon Sep 17 00:00:00 2001
From: George Hotz <geohot@gmail.com>
Date: Tue, 2 Dec 2025 17:26:30 -0800
Subject: [PATCH] add external_test_process_count

---
 test/external/external_test_process_count.py | 57 ++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 test/external/external_test_process_count.py

diff --git a/test/external/external_test_process_count.py b/test/external/external_test_process_count.py
new file mode 100644
index 0000000000..3c54f4bbe7
--- /dev/null
+++ b/test/external/external_test_process_count.py
@@ -0,0 +1,57 @@
+import os, sys, time, multiprocessing
+
+N = int(os.environ.get("NPROC", str(os.cpu_count())))
+DEVICE = os.environ.get("DEV", "AMD")
+
+# this tests the total number of processes that can be running tinygrad at a time
+def proc(i, device, stop_evt):
+  from tinygrad import Tensor
+
+  try:
+    a = Tensor.ones(2, device=device).contiguous()
+    b = Tensor.ones(2, device=device).contiguous()
+    c = (a + b).realize()
+    assert c.tolist() == [2, 2]
+  except Exception as e:
+    # fail if it fails
+    print(f"[child {i:2d}] tinygrad op failed: {e}", file=sys.stderr)
+    # non-zero exit code propagated back to parent
+    sys.exit(1)
+
+  # TODO: wait here for global exit if success. fail if it fails
+  # -> We wait on a global Event shared from the parent.
+  print(f"[child {i:2d}] success")
+  stop_evt.wait()
+  # Normal successful exit
+  sys.exit(0)
+
+if __name__ == "__main__":
+  print(f"testing {N} concurrent tinygrad processes")
+
+  # global exit event, shared by all children
+  stop_evt = multiprocessing.Event()
+  procs = []
+
+  # launch n proc of proc 1 per 200 ms
+  for i in range(N):
+    p = multiprocessing.Process(target=proc, args=(i, DEVICE, stop_evt), name=f"tinygrad-proc-{i}")
+    p.start()
+    procs.append(p)
+    time.sleep(0.1)  # 100 ms between launches
+
+  # signal global exit
+  time.sleep(0.5)
+  stop_evt.set()
+
+  # join all children
+  for p in procs: p.join()
+
+  # check for failures
+  failed = [p for p in procs if p.exitcode != 0]
+  if failed:
+    print(f"{len(failed)} / {len(procs)} processes failed "
+          f"with exit codes: {[p.exitcode for p in failed]}", file=sys.stderr)
+    sys.exit(1)
+
+  print(f"All {len(procs)} tinygrad processes ran successfully")
+  sys.exit(0)