系統技術非業餘研究 » 未公開的erlang ports trace
阿新 • • 發佈：2018-12-23
erlang的trace機制非常強大, 在dbg, ttb模組的配合下, 可以非常清楚的瞭解系統的運作, 排錯, 和調優. 但是有個對於做網路程式重要的功能被忽視了, 沒有寫到文件. 那就是trace ports訊息.
我們的gen_tcp,file都是port實現的, 那麼瞭解這麼模組的運作其實就是要跟蹤系統對ports的開啟, 關閉, 讀寫操作.
好吧,上程式碼的時間了.
由於是未公開的功能, 所以dbg模組預設也是沒啟用這個功能的.我們patch下:
lib/runtime_tools/src/dbg.erl
1128all() -> 1129 [send,'receive',call,procs,garbage_collection,running, 1130 set_on_spawn,set_on_first_spawn,set_on_link,set_on_first_link, 1131 timestamp,arity,return_to, ports]. %%新增ports
重新編譯, 安裝.
[email protected]:~/otp# erl Erlang R14A (erts-5.8) [smp:2:2] [rq:2] [async-threads:0] [kernel-poll:false] Eshell V5.8 (abort with ^G) 1> dbg:tracer(). {ok,<0.33.0>} 2> dbg:p(all, [ports]). {ok,[{matched,[email protected],0}]} 3> ls(). (<0.3.0>) open #Port<0.522> efile (#Port<0.522>) closed normal (<0.3.0>) open #Port<0.523> efile (#Port<0.523>) closed normal (<0.3.0>) open #Port<0.524> efile (#Port<0.524>) closed normal (<0.3.0>) open #Port<0.525> efile (#Port<0.525>) closed normal (<0.3.0>) open #Port<0.526> efile (#Port<0.526>) closed normal .git .gitignore .mailmap AUTHORS ok 4> os:cmd("ls"). (<0.40.0>) open #Port<0.527> '/bin/sh -s unix:cmd 2>&1' (#Port<0.527>) closed {} "aclocal.m4\nAUTHORS\n" (<0.3.0>) open #Port<0.522> efile (#Port<0.522>) closed normal (<0.3.0>) open #Port<0.523> efile (#Port<0.523>) closed normal (<0.3.0>) open #Port<0.524> efile (#Port<0.524>) closed normal (<0.3.0>) open #Port<0.525> efile (#Port<0.525>) closed normal (<0.3.0>) open #Port<0.526> efile (#Port<0.526>) closed normal 5> {ok, F} = file:open("AUTHORS", [read]). (<0.39.0>) open #Port<0.527> efile {ok,<0.39.0>} 6> file:read(F, 1024). {ok,"AUTHORS\n\n Contributions - improvements, fixes, new features - from developers\n make the Erlang 'Open Source' project a success. To give credit\n where it's due, we've added a file called AUTHORS to each\n application sub-directory with a list of everyone who has contributed\n It might also contain the names of the original authors at Ericsson.\n\n Speaking of original authors, we don't want to forget all the people\n working full time with Erlang and OTP. So, thanks to everyone\n working with Erlang at the OTP group, the Computer Science\n Laboratory and the Software Architecture Laboratory.\n\n"} 7> file:close(F). ok 8> (#Port<0.527>) closed normal
這麼簡單的我們透過這個功能可以瞭解到ports的運作(開啟, 關閉)了,多謝otp開發組.
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