fixup! doc: add abnormal termination step 1

documentation/abnormal_termination/step1/using_exit_stack_traces.md

@@ -1,15 +1,43 @@
-# Using `--trace-exit` CLI Option
+# Using Exit Stack Traces for Debugging
 
-`--trace-exit` CLI option will print a stack trace on every proactive `process.exit`
-invocation. It is convenient to confirm if the abnormal exit of the process was
-initiated from an invocation of `process.exit` or something other crashes.
+`--trace-exit` CLI option will print a stack trace on every proactive
+`process.exit` invocation. It is convenient to confirm if the abnormal exit of
+the process was initiated from an invocation of `process.exit` or something
+other crashes.
+
+> Caveat:
+> `--trace-exit` CLI option is available since Node.js v13.5.0.
 
 ## How To
 
+There are conditions that we used an third party library that we have trivial
+knowledge of the implementation details. It is hard to determine where the exit
+is trigger in which library in these conditions. On the first step we have to
+determine if it is a proactive `process.exit` invocation and where it is to
+prevent follow up not trivial work of detailed digging the exit reasons.
+
+The simple step is to add an option `--trace-exit` on starting the Node.js
+process. Since then, we can see a stacktrace on each call of `process.exit`.
+
 ```bash
-> node --trace-exit src/abnormal-exit.js
+ > node --trace-exit src/abnormal-exit.js
+(node:26480) WARNING: Exited the environment with code 0
+    at exit (internal/process/per_thread.js:168:13)
+    at /node_modules/some-obscure-library:199:32 # this is the actual location.
+    at Module._compile (internal/modules/cjs/loader.js:1139:30)
+    at Module._extensions..js (internal/modules/cjs/loader.js:1159:10)
+    at Module.load (internal/modules/cjs/loader.js:988:32)
+    at Module._load (internal/modules/cjs/loader.js:896:14)
+    at executeUserEntryPoint (internal/modules/run_main.js:71:12)
 ```
 
+With the knowledge of where the calls of `process.exit` is, we can check around
+the invocation to guess the reasons and prevent it from abnormal exits.
+
+Or if we find there is no such prints on process exits, we can come to a
+conclusion that the process may exited for some other obscure reasons, and we
+have to deploy following steps of the Abnormal Termination guides.
+
 ## Useful Links
 
 - https://nodejs.org/docs/latest/api/cli.html#cli_trace_exit