Kord Extensions•6mo ago

ConcurrentModificationException errors

So today I finally released by bot to production, which was scary because it meant going from 3 servers to 16k servers... so of course I expected errors. This error is popping up on various places on my bot when accessing stuff from Discord. I'm using: defaultStrategy = EntitySupplyStrategy.cacheWithCachingRestFallback. This is happening in various functions that interact with Discord data in some way, in the particular stacktrace I attached, it refers to this call:

private suspend fun EventContext<MemberLeaveEvent>.onMemberLeft() {
        val world = nabBot.serverWorldMapping[event.guild.longId]
        val botMember = event.guild.selfMember()  // <-- this line
        webhookManager.sendLogMessage(event.guild) {
            // More code
        }
}

private suspend fun EventContext<MemberLeaveEvent>.onMemberLeft() {
        val world = nabBot.serverWorldMapping[event.guild.longId]
        val botMember = event.guild.selfMember()  // <-- this line
        webhookManager.sendLogMessage(event.guild) {
            // More code
        }
}

event { action { onMemberLeft() } }

event { action { onMemberLeft() } }

This is happening in many different places, with stuff that interacts with the entity supplier or with Flows.

stacktrace.txt

Solution:

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48 Replies

gdude•6mo ago

That looks like a problem with Kord, so I'll have to defer to @Kord Team Members While you wait, make sure you're using the latest KordEx snapshot and not providing your own Kord version

Unknown User•6mo ago

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SchlaubiBus•6mo ago

We should as I published 0.5.1 a few days ago

Unknown User•6mo ago

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SchlaubiBus•6mo ago

yeah I think this was largely resolved by changing it in kord, however cache doesn't change it for now

Unknown User•6mo ago

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GalarzaaOP•6mo ago

I will give this a try I'm actually in the 1.8.0 SNAPSHOT, tried 1.8.1, but I was getting these issues: https://canary.discord.com/channels/1121419906995458098/1252310860551028767

Unknown User•6mo ago

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gdude•6mo ago

you got that while matching the kordex build environment? is 0.5.1 not part of 0.14.0-SNAPSHOT?

Unknown User•6mo ago

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gdude•6mo ago

was there a new cycle that I missed?

Unknown User•6mo ago

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gdude•6mo ago

Oh huh, was the new cycle announced? Maybe I forgot about it

Unknown User•6mo ago

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gdude•6mo ago

That's not explicit enough imo haha But yeah, fair

Unknown User•6mo ago

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gdude•6mo ago

Yeah, I think there's been some releases I should test But I kinda wanna get a web PoC merged first before I go doing more mainline

Unknown User•6mo ago

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gdude•6mo ago

Ah nice, that's good news Thanks

GalarzaaOP•6mo ago

Just switched to temurin image, added useKSP2 and other gradle.properties flags you are using, Kotlin 1.9.22 But what I get is a different error:

114.5 Execution failed for task ':nabbot-discord-bot:kspKotlin'.
114.5 > A failure occurred while executing com.google.devtools.ksp.gradle.KspAAWorkerAction
114.5    > javaslang/collection/HashMap

114.5 Execution failed for task ':nabbot-discord-bot:kspKotlin'.
114.5 > A failure occurred while executing com.google.devtools.ksp.gradle.KspAAWorkerAction
114.5    > javaslang/collection/HashMap

(should I continue this specific discussion on the other thread or here?)

gdude•6mo ago

The other thread if you would

SchlaubiBus•6mo ago

javaslang/collection/HashMap 🤔

gdude•6mo ago

Huh, yeah

SchlaubiBus•6mo ago

running with --stacktrace might help

GalarzaaOP•6mo ago

Ok, I got over the KSP2 issues, I'm on 1.81 snapshot now. I upgraded kotlin (and ksp) to 1.9.24 and that did it. Now, when trying to add kord cache, it is not resolved, am I missing a maven repository? I'm using the ones in Kord's README

Unknown User•6mo ago

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SchlaubiBus•6mo ago

The artifact stuff should be fixed in 5-10 mins, I am working on it, but Maven central changed their publishing and since different projects are on different hosts it caused issues

SchlaubiBus•6mo ago

But the core issue should be fixed since this commit

GitHub

Some internal improvments · kordlib/gradle-tools@49a9962

SchlaubiBus•6mo ago

0.5.3 should be available in around 10 minutes (maven central sync) and then it should work

Solution

Unknown User•6mo ago

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GalarzaaOP•6mo ago

So I tried with 0.5.3 and it builds fine, but it fails on startup

GalarzaaOP•6mo ago

Stacktrace

GalarzaaOP•6mo ago

(fixed extension)

Full_Stacktrace.txt

Unknown User•6mo ago

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GalarzaaOP•6mo ago

This is looking good, haven't seen any ConcurrentModificationExceptions so far, thanks!

SchlaubiBus•6mo ago

I think the jdk concurrenthashmap can't even throw such an exception

Unknown User•6mo ago

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SchlaubiBus•6mo ago

I mean the ConcurrentMutableMap is called concurrent too I wonder how the ConcurrentHashMap works since it's supposed to be lock free

Unknown User•6mo ago

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SchlaubiBus•6mo ago

I wonder whether that's a jvm specific bug or a general stately bug

Unknown User•6mo ago

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SchlaubiBus•6mo ago

https://github.com/touchlab/Stately/issues/105

GitHub

java.util.ConcurrentModificationException:, even when using statel...

Exception java.util.ConcurrentModificationException: at java.util.ArrayList$Itr.next (ArrayList.java:860) at co.touchlab.stately.collections.ConcurrentMutableIterator$next$1.invoke (ConcurrentMutab...

Unknown User•6mo ago

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SchlaubiBus•6mo ago

that makes sense

Unknown User•6mo ago

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SchlaubiBus•6mo ago

LockSupport 👀 wonder how loom changes it

Unknown User•6mo ago

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SchlaubiBus•6mo ago

Yeah they rewrote LockSupport for loom they said that in some talks

Gaming

Programming

ConcurrentModificationException errors