739418 - If a rethrown exception is uncaught, report the stack trace of the original exception, not the rethrowing exception

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: General, defect)

Description

[Chris Peterson [:cpeterson]]

A rethrown exception's stack trace lists the rethrowing exception before the original exception (the `cause`). When reviewing crash reports in Socorro, unrelated crashes may look like dupes because their stack traces point to the same rethrowing error handler. If we move the original exception to the top of the crash report, Socorro can correctly collate related crash reports.

Examples of unrelated bugs that may look like dupes: bug 734624, bug 738977, and bug 738976.

Comment 1

[Chris Peterson [:cpeterson]]

Attachment: bug-739418-report-rethrown-exceptions.patch

When reporting a rethrown exception, report the original exception's stack trace.

Comment 2

[Brad Lassey [:blassey] (use needinfo?)]

Comment on attachment 609499 [details] [diff] [review]
bug-739418-report-rethrown-exceptions.patch

Review of attachment 609499 [details] [diff] [review]:
-----------------------------------------------------------------

::: mobile/android/base/GeckoAppShell.java
@@ +161,5 @@
>              public void uncaughtException(Thread thread, Throwable e) {
> +                String stackTrace = getStackTraceString(e);
> +
> +                Throwable cause = e.getCause();
> +                if (cause != null) {

should this be while(cause != null)?

I'd do it this way:

Throwable cause;
while (null != (cause = e.getCause()))
   e = cause;
reportJavaCrash(getStackTraceString(e));

Comment 3

[Chris Peterson [:cpeterson]]

Attachment: bug-739418-report-rethrown-exceptions-v2.patch

If the uncaught exception was rethrown, walk the exception `cause` chain to find the original exception.

Comment 4

[Brad Lassey [:blassey] (use needinfo?)]

Comment on attachment 609816 [details] [diff] [review]
bug-739418-report-rethrown-exceptions-v2.patch

Review of attachment 609816 [details] [diff] [review]:
-----------------------------------------------------------------

::: mobile/android/base/GeckoAppShell.java
@@ +169,2 @@
>                  Log.e(LOGTAG, ">>> REPORTING UNCAUGHT EXCEPTION FROM THREAD "
>                                + thread.getId() + " (\"" + thread.getName() + "\")", e);

its probably worth moving this logging above the walking since it will include all the stacks

Comment 5

[Chris Peterson [:cpeterson]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/1dd339df6a7c

Comment 6

[Chris Peterson [:cpeterson]]

Comment on attachment 609816 [details] [diff] [review]
bug-739418-report-rethrown-exceptions-v2.patch

[Approval Request Comment]
Regression caused by (bug #): N/A
User impact if declined: Socorro crash reports will be harder to diagnose.
Testing completed (on m-c, etc.): 
Risk to taking this patch (and alternatives if risky): Low. Java only code that is only executed when reporting an uncaught exception.
String changes made by this patch: None

Comment 7

[Chris Peterson [:cpeterson]]

https://hg.mozilla.org/mozilla-central/rev/1dd339df6a7c

Comment 8

[Alex Keybl [:akeybl]]

Comment on attachment 609816 [details] [diff] [review]
bug-739418-report-rethrown-exceptions-v2.patch

[Triage Comment]
Low risk, mobile-only fix. Approved for Aurora 13.

Comment 9

[Chris Peterson [:cpeterson]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/5c0f104db5e9

Comment 10

[Chris Peterson [:cpeterson]]

Comment on attachment 609816 [details] [diff] [review]
bug-739418-report-rethrown-exceptions-v2.patch

If we are going to land bug 701002 to improve Java crash reporting on ESR10, then I recommend also landing this patch to make Java crash reports easier to collate in Socorro.

Comment 11

[Alex Keybl [:akeybl]]

Comment on attachment 609816 [details] [diff] [review]
bug-739418-report-rethrown-exceptions-v2.patch

[Triage Comment]
Approved for ESR10 in support of crash killing. This has already had time to bake on Nightly/Aurora.

Comment 12

[Chris Peterson [:cpeterson]]

https://hg.mozilla.org/releases/mozilla-esr10/rev/4246cbfe8c4b