feature: allow ngx.sleep to be used blockingly in non-yieldable phases #1759

spacewander · 2020-07-29T02:11:50Z

Allow ngx.sleep everywhere simplify the application's logic.
Now we don't need to write a fallback if the same function need to be
run in non-yieldable phases.

Close #1730.

I hereby granted the copyright of the changes in this pull request
to the authors of this lua-nginx-module project.

Allow ngx.sleep everywhere simplify the application's logic. Now we don't need to write a fallback if the same function need to be run in non-yieldable phases. Close openresty#1730.

rainingmaster

should we have a different log format for sleep in non NGX_HTTP_LUA_CONTEXT_YIELDABLE? Or we could log with phase in the debug log?

src/ngx_http_lua_sleep.c

spacewander · 2020-07-29T09:47:49Z

@rainingmaster @dndx
Updated.

doujiang24 · 2020-07-30T15:00:01Z

doc/HttpLuaModule.wiki


-Sleeps for the specified seconds without blocking. One can specify time resolution up to 0.001 seconds (i.e., one millisecond).
+Sleeps for the specified seconds without blocking in yieldable phases or blockingly in other phases.


we'd better clarify the blockingly phases.

and we need to highlight it's not recommended to use it in the non-yieldable phase since it will block the whole nginx worker process.

agentzh · 2020-08-12T02:29:02Z

README.markdown

@@ -5621,14 +5621,17 @@ ngx.sleep

 **syntax:** *ngx.sleep(seconds)*

-**context:** *rewrite_by_lua&#42;, access_by_lua&#42;, content_by_lua&#42;, ngx.timer.&#42;, ssl_certificate_by_lua&#42;, ssl_session_fetch_by_lua&#42;*
+**context:** *init_by_lua&#42;, init_worker_by_lua&#42;, set_by_lua&#42;, rewrite_by_lua&#42;, access_by_lua&#42;, content_by_lua&#42;, header_filter_by_lua&#42;, body_filter_by_lua&#42;, log_by_lua&#42;, ngx.timer.&#42;, balancer_by_lua&#42;, ssl_certificate_by_lua&#42;, ssl_session_fetch_by_lua&#42;, ssl_session_store_by_lua&#42;, exit_worker_by_lua&#42;*


It's not safe to use blocking sleeps in certain contexts like init_worker_by_lua*, set_by_lua*, header_filter_by_lua*, and etc.

I'm fine with enabling it in contexts where blocking operations do not matter, like in init_by_lua* and exit_worker_by_lua*. Otherwise it's too dangerous.

mergify · 2021-09-20T10:04:51Z