sqlite3.dylib: illegal multi-threaded access to database connection
It turns out that SQLITE_CONFIG_MULTITHREAD
mode works well on a multi-threading environment as long as you don't use the same connection simultaneously; which happen to be the exact scenario that I had. Therefore, to solve this issue you can either open a new connection for each thread or use SQLITE_CONFIG_SERIALIZED
in full mutex mode using SQLITE_OPEN_FULLMUTEX
flag to open the connection.
The helper method ended up like so:
+(sqlite3*) getInstance {
if (instance == NULL) {
sqlite3_shutdown();
sqlite3_config(SQLITE_CONFIG_SERIALIZED);
sqlite3_initialize();
NSLog(@"isThreadSafe %d", sqlite3_threadsafe());
const char *path = [@"./path/to/db/db.sqlite" cStringUsingEncoding:NSUTF8StringEncoding];
if (sqlite3_open_v2(path, &database, SQLITE_OPEN_READWRITE|SQLITE_OPEN_FULLMUTEX, NULL) != SQLITE_OK) {
NSLog(@"Database opening failed!");
}
}
return instance;
}
Use please SQLite Shared-Cache Mode https://www.sqlite.org/sharedcache.html
sqlite3_open_v2(path.path, &db, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_SHAREDCACHE, nil) != SQLITE_OK
SQLITE_OPEN_SHAREDCACHE
Reliable 100% :)
In case of any one faced this problem in Swift. Solution will be:
let dbName = "first.db"
static let shared = DatabaseManger()
var db: OpaquePointer?
private init(){
print("singletone initialized")
sqlite3_shutdown();
let dbPath = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
.appendingPathComponent(dbName)
if sqlite3_open_v2(dbPath.path, &db, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_FULLMUTEX, nil) == SQLITE_OK {
print("Successfully opened database connection at \(dbPath.path)")
}
else {
print("unable to open database connection")
}
}
This code tested in swift version 4.0 and 4.2