new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_thread.h
@@ -0,0 +1,74 @@
+#ifndef _NGX_THREAD_H_INCLUDED_
+#define _NGX_THREAD_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+#if (NGX_THREADS)
+
+#if (USE_RFORK)
+
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <sched.h>
+
+typedef pid_t  ngx_tid_t;
+
+#define TID_T_FMT      PID_T_FMT
+
+#define ngx_log_tid    0
+
+#undef ngx_log_pid
+#define ngx_log_pid    ngx_thread_self()
+
+
+#define NGX_MUTEX_LIGHT      1
+#define NGX_MUTEX_CV         2
+
+#define NGX_MUTEX_LOCK_BUSY  0x80000000
+
+typedef struct {
+    ngx_atomic_t  lock;
+    ngx_log_t    *log;
+    int           semid;
+} ngx_mutex_t;
+
+
+#else /* use pthreads */
+
+#include <pthread.h>
+
+typedef pthread_t  ngx_tid_t;
+
+#define ngx_log_tid    ngx_thread_self()
+
+#endif
+
+
+ngx_int_t ngx_init_threads(int n, size_t size, ngx_log_t *log);
+int ngx_create_thread(ngx_tid_t *tid, int (*func)(void *arg), void *arg,
+                      ngx_log_t *log);
+ngx_tid_t ngx_thread_self();
+
+ngx_mutex_t *ngx_mutex_init(ngx_log_t *log, uint flags);
+void ngx_mutex_done(ngx_mutex_t *m);
+
+#define ngx_mutex_trylock(m)  ngx_mutex_do_lock(m, 1)
+#define ngx_mutex_lock(m)     ngx_mutex_do_lock(m, 0)
+ngx_int_t ngx_mutex_do_lock(ngx_mutex_t *m, ngx_int_t try);
+ngx_int_t ngx_mutex_unlock(ngx_mutex_t *m);
+
+
+#else /* !NGX_THREADS */
+
+#define ngx_log_tid  0
+#define TID_T_FMT    "%d"
+
+#define ngx_mutex_lock(m)
+#define ngx_mutex_unlock(m)
+
+#endif
+
+
+#endif /* _NGX_THREAD_H_INCLUDED_ */