IO error: lock /data/user/0/org.thunderdog.challegram/files/pmc/db/LOCK: already held by process

[vkryl]

Crash while trying to open settings database 59,053 reports, 11,542 impacted users as of 27th March 2020.

AssertionError: Java_org_thunderdog_challegram_N_dbOpen:94: IO error: lock /data/user/0/org.thunderdog.challegram/files/pmc/db/LOCK: already held by process, versionCode: 1314020

at org.drinkmore.Tracer$b.run(SourceFile
  at java.lang.Thread.run (Thread.java:929)

Such issue could happen if Settings.instance() is referenced somewhere inside Settings constructor, i.e. accidental usage of custom log system instead of android.util.Log, etc. But could not find anything promising.

Another potential cause is that somehow Settings object gets killed, but finalize() which causes database being left open.

[vkryl]

It seems the amount of reports might be significantly reduced by closing #61.