malloc_ptr classes(objc_copyClassList(&numClasses), &free); crash

[huanglins]

How frequently does the bug occur?

All the time

Description

Crashing on iOS 14.1, iOS 14.8 devices

Stacktrace & log output

No response

Can you reproduce the bug?

Yes, always

Reproduction Steps

try? Realm(configuration: config)

let rlmRealm = try RLMRealm(configuration: configuration.rlmConfiguration, queue: queue)

RLMSchema *schema = configuration.customSchema ?: RLMSchema.sharedSchema;

malloc_ptr classes(objc_copyClassList(&numClasses), &free); -> crash

Version

10.20 、10.32.3

What SDK flavour are you using?

Local Database only

Are you using encryption?

No, not using encryption

Platform OS and version(s)

iOS

Build environment

Xcode version: ... 14.1
Dependency manager and version: ... pod 1.11.3

[huanglins]

When i added monitorextension i got this error

[huanglins]

After specifying objectTypes in Realm.Configuration, the startup will not crash, but you can still hope to fix the problem

[dianaafanador3]

Hi @huanglins from what I can understand your issue disappeared when specifying the objectTypes you want in your schema, which means that this issues is happening when doing a complete discovery to build the schema. When you open the realm we do a schema discovery for all the classes and then filter the ones that inherit from Object or RLMObject so we can build the schema for the realm.
You mentioned that this is happening when adding a monitor extension which makes me suspect that objc_copyClassList() is crashing due to running out of memory.

We could probably document this better, but your solution is right now the best to solve this issue.

[kaibaaqua]

I have the same problem with Realm 10.32.3, but it was OK with Realm 10.27.0.

I don't know what the monitorextension is.

By applying @huanglins 's workaround (specifying the objectTypes).

[liujieyuu]

Let me give you an example：
let config = Realm.Configuration(fileURL: URL(string: fileURL), schemaVersion: schemaVersion,migrationBlock: { (migration, oldSchemaVersion) in
// 目前我们还未进行数据迁移，因此 oldSchemaVersion == 0
if oldSchemaVersion < 1 {
// 什么都不要做！Realm 会自行检测新增和需要移除的属性，然后自动更新硬盘上的数据库架构
}
// 低版本的数据库迁移......
if migrationBlock != nil {
migrationBlock!(migration, oldSchemaVersion)
}
}, objectTypes: [GoodsItermModel_db.self])

@nirinchev look this

[nirinchev]

This is definitely not enough information to reproduce the issue - it shows creating a simple config and we have many tests that verify code like this works. If you can reproduce a crash in a simple and isolated project, please share the entire project.

[liujieyuu]

Suffice it to say, this is a temporary solution, after all, such a crash is not guaranteed, thank you. @nirinchev