Fixes #2068 - Silent thread leak on exception in completeValueForList #2359
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dfa1
reviewed
May 24, 2021
| .type(newTypeWiring("Query") | ||
| .dataFetcher("pets", new StaticDataFetcher(['cats': cats, 'dogs': dogs]))) | ||
| .type(newTypeWiring("Cat") | ||
| .dataFetcher("toys", new StaticDataFetcher(new List<Object>() { |
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maybe a Collections.singletonList is better here? size returns 1, but then toArrray, listIterator returns both null
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my bad, just spotted the "iterator" that throws exception!
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@KammererTob what about:
new java.util.AbstractList<>() {
@Override
public int size() {
return 1;
}
@Override
public Object get(int index) {
throw new RuntimeException("simulated failure");
}
};
by default, the Iterator will call get(), throwing exception, like in your code.
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Thanks for the feedback. I've adjusted the code as by your comment and i also renamed the whole test block to better reflect what it is testing.
bbakerman
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This an attempt to fix #2068 . It might be a bit too naive, but i wanted to get another set of eyes on this issue.
Here my reasoning for this fix:
As explained in the issue, the problem lies in how the dataloader determines when to dispatch different levels. When one of the
resolveFieldWithInfofutures completes exceptionally, theAsync.eachFuture also completes exceptionally and the dataloader instrumentation is not made aware of this. SinceexpectedStrategyCallsPerLevelis increased by calls tohandleOnFieldValuesInfoby previous levels andallOnFieldCallsHappenedis checked for the previous level when dispatching, it means that all deeper levels will never be dispatched (expectedStrategyCallsPerLevelis bigger thanhappenedOnFieldValueCallsPerLevel) and we leak a thread. The changes made make sure that the instrumentation is made aware of this exceptional completion and thus that deeper levels can still be dispatched.If you have better ideas to fix this i am open for your suggestions! Thanks!