"Cookie sqlite error 5, errno 0: database is locked" when running unit tests

[Olivier Tilloy]

I’ve observed the following error a couple of times (out of hundreds of test runs) when running the unit tests on my laptop:

[0202/153311:ERROR:connection.cc(1060)] Cookie sqlite error 5, errno 0: database is locked, sql: PRAGMA journal_mode = PERSIST
[0202/153311:FATAL:connection.cc(747)] SQL compile error database is locked
 [0x7fd4b70ad886] base::debug::StackTrace::StackTrace()
 [0x7fd4b7119413] logging::LogMessage::~LogMessage()
 [0x7fd4bb12acf9] sql::Connection::GetUntrackedStatement()
 [0x7fd4bb12b125] sql::Connection::DoesTableOrIndexExist()
 [0x7fd4bb12b0c0] sql::Connection::DoesTableExist()
 [0x7fd4bb13226f] sql::MetaTable::DoesTableExist()
 [0x7fd4bb13278d] sql::MetaTable::Init()
 [0x7fd4bb5d08db] content::SQLitePersistentCookieStore::Backend::EnsureDatabaseVersion()
 [0x7fd4bb5cef1f] content::SQLitePersistentCookieStore::Backend::InitializeDatabase()
 [0x7fd4bb5cd7b6] content::SQLitePersistentCookieStore::Backend::LoadAndNotifyInBackground()
 [0x7fd4bb5db9d7] base::internal::RunnableAdapter<>::Run()
 [0x7fd4bb5da205] base::internal::InvokeHelper<>::MakeItSo()
 [0x7fd4bb5d8d21] base::internal::Invoker<>::Run()
 [0x7fd4b709c572] base::Callback<>::Run()
 [0x7fd4b71df56e] base::SequencedWorkerPool::Inner::ThreadLoop()
 [0x7fd4b71ddb99] base::SequencedWorkerPool::Worker::Run()
 [0x7fd4b71e9784] base::SimpleThread::ThreadMain()
 [0x7fd4b71dc320] base::(anonymous namespace)::ThreadFunc()
 [0x7fd4e6db7182] start_thread
 [0x7fd4e70c7b5d] clone

This looks like a race condition of some sort.

[Chris Coulson (chrisccoulson)]

This looks like another context still has the database open. Is it possible for the next test to start before all resources from the previous test have been deleted? If that's the case, there's probably a qtquick bug here.