Read and Understand logs

What is the efficient debugging way? reading logs. Manually testing each options makes things difficult and time-consuming. If we read the logs we get to know why we are receiving such unexpected outcome. Because \(n\)-different factors can lead to same outcome.

Logs have too much information not all are necessary to understand why we are receiving specific output.

Steps

1. First answer the question : What decision did the system make that surprised me?
2. Ask:
   • What system produced these logs?
   • What subsystems exist inside it?
     example: for a mail synchronization issue we look for
   • MailSyncWorker → syncing
   • MessagingController → high-level mail logic
   • NotificationController → notifications
   • PushController → push vs polling
   • Android WorkManager → scheduling

3. List down the events and their timeline (with search)

   Time	What happened
   07:32:39	App process starts
   07:32:39–47	Background mail sync runs
   …	…

4. Separate signals form noise
   • Verbs about decisions (D)
   • Words like: start, stop, clear, disable, success, cancelled, no new, already present.
     Example signal:

    7:32:39      Scheduling work ID ... MailSyncWorker
       
    7:32:39      Executing periodic mail sync
    7:32:39      Running command 'checkMail'
    7:32:39      Starting mail check
    7:32:40      Synchronizing account ..
       
    7:32:40      Connecting to imap.gmail.com
    7:32:42      authenticated (Success)
       
    7:32:45      EXAMINE "INBOX"
    7:32:46      Remote message count for folder INBOX is 2
       
    ....
   

5. Track state transition. Build the mental model of the workflow from such logs

   12-24 07:32:47.xxx  8541  8577 D ImapSync: Have 0 unsynced messages
   

Ignore the irrelevant logs that are not specific to your issue. like OEM, UI, darkmode, library loading, …

Breakdown of Log

12-24        → Date (MM-DD)
07:32:47.xxx → Time (HH:MM:SS.milliseconds) — local device time
8541         → Process ID (PID)
8577         → Thread ID (TID)
D            → Log level (DEBUG)
ImapSync     → Component / class emitting the log
Message      → Actual event

Log Levels Reference

Level	Read when	Why
V	Rarely	Too detailed
D	Always	Real behavior
I	Always	Phase confirmation
W	Carefully	Unexpected but handled
E	Immediately	Failure
F	Drop everything	Crash

Practice set