doc: documented the new ngx.worker.pid() API.

README.markdown

@@ -173,6 +173,7 @@ Table of Contents
     * [ngx.config.nginx_version](#ngxconfignginx_version)
     * [ngx.config.ngx_lua_version](#ngxconfigngx_lua_version)
     * [ngx.worker.exiting](#ngxworkerexiting)
+    * [ngx.worker.pid](#ngxworkerpid)
     * [ndk.set_var.DIRECTIVE](#ndkset_vardirective)
     * [coroutine.create](#coroutinecreate)
     * [coroutine.resume](#coroutineresume)
@@ -5793,6 +5794,19 @@ This API was first introduced in the `0.9.3` release.
 
 [Back to TOC](#table-of-contents)
 
+ngx.worker.pid
+--------------
+
+**syntax:** *pid = ngx.worker.pid()*
+
+**context:** *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*, init_by_lua*, init_worker_by_lua**
+
+This function returns a Lua number for the process ID (PID) of the current Nginx worker process. This API is more efficient than `ngx.var.pid` and can be used in contexts where the [ngx.var.VARIABLE](#ngxvarvariable) API cannot be used (like [init_worker_by_lua](#init_worker_by_lua)).
+
+This API was first introduced in the `0.9.5` release.
+
+[Back to TOC](#table-of-contents)
+
 ndk.set_var.DIRECTIVE
 ---------------------
 **syntax:** *res = ndk.set_var.DIRECTIVE_NAME*

doc/HttpLuaModule.wiki

@@ -4919,6 +4919,16 @@ This function returns a boolean value indicating whether the current Nginx worke
 
 This API was first introduced in the <code>0.9.3</code> release.
 
+== ngx.worker.pid ==
+
+'''syntax:''' ''pid = ngx.worker.pid()''
+
+'''context:''' ''set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*, init_by_lua*, init_worker_by_lua*''
+
+This function returns a Lua number for the process ID (PID) of the current Nginx worker process. This API is more efficient than <code>ngx.var.pid</code> and can be used in contexts where the [[#ngx.var.VARIABLE|ngx.var.VARIABLE]] API cannot be used (like [[#init_worker_by_lua|init_worker_by_lua]]).
+
+This API was first introduced in the <code>0.9.5</code> release.
+
 == ndk.set_var.DIRECTIVE ==
 '''syntax:''' ''res = ndk.set_var.DIRECTIVE_NAME''