use SwitchToThread() instead of Sleep(0), because the later
may not yield control, if there is no thread with higher priority
diff --git a/src/os/win32/ngx_process.h b/src/os/win32/ngx_process.h
index 55f5648..235b250 100644
--- a/src/os/win32/ngx_process.h
+++ b/src/os/win32/ngx_process.h
@@ -52,7 +52,7 @@
ngx_pid_t ngx_execute(ngx_cycle_t *cycle, ngx_exec_ctx_t *ctx);
#define ngx_debug_point()
-#define ngx_sched_yield() Sleep(0)
+#define ngx_sched_yield() SwitchToThread()
#define NGX_MAX_PROCESSES (MAXIMUM_WAIT_OBJECTS - 4)
