Xcode "Hang Risk" warning due to "itemsSemaphore.wait()" priority inversion. about grdb.swift HOT 2 CLOSED

Hello @leotumwattana,

This is a warning about sub-optimal use of threads. Check Apple documentation Diagnosing performance issues early in order to understand what this warning is about.

There are already a few GRDB issues opened about priority inversion warnings. Take care that some applications instruct GRDB to perform the wrong actions: it's important that you understand the above Apple documentation. By default, all database operations run with the userInitiated quality of service (see Configuration.qos).

Finally, check if your application performs any synchronous database access from an asynchronous Task:

// WRONG APPLICATION PATTERN

// An async function...
func asyncFunction() async throws {
    try performSyncDatabaseAccess()
}

func performSyncDatabaseAccess() throws {
    // ...should not call a synchronous database access method.
    try dbPool.read { db in... } // sync
}

If this happens, refactor your app so that all database accesses performed from a Task are asynchronous:

// CORRECT APPLICATION PATTERN

// An async function...
func asyncFunction() async throws {
    try await performAsyncDatabaseAccess()
}

func performAsyncDatabaseAccess() async throws {
    // ...can call asynchronous database access methods.
    try await dbPool.read { db in... } // async
}

from grdb.swift.

Thanks @groue!

from grdb.swift.