node: don't abort on invalid -dbcache in settings.json #36347

1. 
   0xShadowX commented at 5:16 PM on September 26, 2026: none

   LogOversizedDbCache (added in #33333) is noexcept, but it reads -dbcache through CalculateDbCacheBytes -> GetIntArg. GetIntArg throws when settings.json has a number that isn't an integer or doesn't fit in int64, e.g. {"dbcache": 4096.5}. The exception hits the noexcept boundary and bitcoind aborts during startup:

   libc++abi: terminating due to uncaught exception of type std::runtime_error: JSON integer out of range
   

   This removes noexcept. The exception now reaches the handler in AppInit, and the node exits with status 1 and an error message instead of aborting:

   EXCEPTION: St13runtime_error
   JSON integer out of range
   bitcoin in AppInit()
   

   The added case in feature_settings.py writes {"dbcache": 4096.5} to settings.json and checks that startup fails with that message from AppInit.

2. 
   DrahtBot commented at 5:16 PM on September 26, 2026: contributor

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   • Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36347
   • Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36347.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36347#author-ralph

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3. in test/functional/feature_settings.py:89 in 75e297d791 outdated

     84 | @@ -85,6 +85,11 @@ def run_test(self):
     85 |              fp.write('{"key": 1, "key": 2}')
     86 |          node.assert_start_raises_init_error(expected_msg='Found duplicate key key in settings file', match=ErrorMatch.PARTIAL_REGEX)
     87 |  
     88 | +        # Test a non-integer dbcache value is reported by AppInit instead of aborting
     89 | +        with settings.open("w") as fp:
   

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   Hamza1610 commented at 7:20 PM on October 7, 2026:

   I would suggest that there is test for integer eg. 4096. makes

   ---

   

   0xShadowX commented at 8:49 PM on October 7, 2026:

   Added a test with dbcache: 4096 in 47e3f3633e: the node starts and the value is read from the settings file. I put it before the non-integer case so the later -nosettings checks still see an invalid settings file.

4. 
   Hamza1610 commented at 7:22 PM on October 7, 2026: none

   Concept ACK

5. 0xShadowX force-pushed on Oct 7, 2026
6. 
   Hamza1610 commented at 12:53 PM on October 8, 2026: none

   ACK 47e3f36

7. sedited requested review from l0rinc on Oct 8, 2026
8. DrahtBot added the label CI failed on Oct 9, 2026
9. 
   maflcko commented at 4:44 PM on October 13, 2026: member

   The ci fails. Can this be closed, or are you still working on this?

10. node: don't abort on invalid -dbcache in settings.json

    LogOversizedDbCache is noexcept, but it reads -dbcache through
    GetIntArg, which throws when settings.json holds a number that is not
    an integer or doesn't fit in int64 (e.g. {"dbcache": 4096.5}). The
    exception hits the noexcept boundary and std::terminate aborts
    bitcoind during startup.
    
    Remove noexcept so the exception reaches AppInit like it does for other
    integer settings, and the node exits with an error message instead of
    aborting.

    2e00693220
11. 0xShadowX force-pushed on Oct 13, 2026
12. 
    0xShadowX commented at 8:32 PM on October 13, 2026: none

    The failure was in the new test, not the fix: {"dbcache": 4096} triggers the oversized-dbcache warning on the 7 GiB macOS runner, and the unexpected stderr fails stop_node. Switched the test values to 300 / 300.5, which stay below the 450 MiB floor of ShouldWarnOversizedDbCache, so the warning can't fire on any machine. Still interested in getting this in.

13. DrahtBot removed the label CI failed on Oct 20, 2026
14. DrahtBot requested review from Hamza1610 on Nov 1, 2026
15. 
    Hamza1610 commented at 9:34 PM on November 1, 2026: none

    re-ACK https://github.com/bitcoin/bitcoin/commit/2e00693220d8fae784906f802892c60cba718fb2

16. 
    sedited commented at 7:35 PM on November 4, 2026: contributor

    I don't know about this patch. This is a crash that is basically only reachable if the user does something very weird. Imo just crashing seems preferable for these cases?

17. 
    0xShadowX commented at 8:01 PM on November 4, 2026: none

    Fair point, a crash on a hand-edited, nonsensical settings.json is arguably the right behaviour. Closing, thanks for taking a look.

18. 0xShadowX closed this on Nov 4, 2026

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Contributors

0xShadowXDrahtBotHamza1610maflckosedited

Review Requested
l0rincHamza1610