deadlock

existingObjectWithID deadlock with NSPrivateQueueConcurrencyType

由 两盒软妹~` 提交于 2019-12-06 03:42:52
问题 I'm running in to a freeze (deadlock?) with the NSPrivateQueueConcurrencyType concurrency type and not with the NSMainQueueConcurrencyType . My context initialization: _managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]; [_managedObjectContext setPersistentStoreCoordinator:coordinator]; The troublesome code: NSManagedObjectID *managedObjectID = [self managedObjectIDForEntity:entity withParseObjectId:object.objectId]; managedObject =

“FOR UPDATE” v/s “LOCK IN SHARE MODE” : Allow concurrent threads to read updated “state” value of locked row

由 断了今生、忘了曾经 提交于 2019-12-06 03:41:37
问题 I have the following scenario: User X logs in to the application from location lc1: call it Ulc1 User X (has been hacked, or some friend of his knows his login credential, or he just logs in from a different browser on his machine,etc.. u got the point) logs in at the same time from location lc2: call it Ulc2 I am using a main servlet which : - gets a connection from database pooling - sets autocommit to false - executes a command that goes through app layers: if all successful, set

What is the proper way to access BerkeleyDB with Perl?

由 為{幸葍}努か 提交于 2019-12-06 02:39:45
问题 I've been having some problems with using BerkeleyDB. I have multiple instances of the same code pointed to a single repository of DB files, and everything runs fine for 5-32 hours, then suddenly there is a deadlock. The command prompts stop right before executing a db_get or db_put or cursor creation call. So I'm simply asking for the proper way to handle these calls. Here's my general layout: This is how the environment and DBs are created: my $env = new BerkeleyDB::Env ( -Home => "

SQL Server 2008: Getting deadlocks… without any locks

由 我的梦境 提交于 2019-12-06 01:24:39
问题 I'm currently conducting some experiments on a SQL Server 2008 database. More specifically, I have a JDBC application that uses hundreds of concurrent threads to execute thousands of tasks, each of which runs the following query on the database: UPDATE from Table A where rowID='123' However, I'm getting a ton of deadlock errors (SQL Exception 1205) whenever I set the isolation level to be higher than READ_UNCOMMITTED. It happens even if I set row locking, table locking, and exclusive lock

Deadlock while blocking async HttpClient call within a task continuation

由 喜欢而已 提交于 2019-12-06 01:21:51
I am trying to wrap my head around synchronously calling async functions and deadlock. In the below example I am blocking an async call which internally uses ConfigureAwait(false) which as far as I can tell should prevent deadlock. The first call to the web service does not deadlock. However, the second one that happens within a continuation that syncs back to the UI thread deadlocks. GetBlocking_Click is a click event in a WPF app so both the first and the second request happen on the UI thread. private void GetBlocking_Click(object sender, RoutedEventArgs e) { const string uri = "http://www

interpreting jstack output

由 天涯浪子 提交于 2019-12-06 01:06:51
I have a java process loading a lot of data from a bunch of .csv files into a Neo4j database using the BatchInserter . I was using: OpenJDK 7 Ubuntu 12.04 Neo4j 2.0 M3 After loading the first 164 GB (according to ls -lh ) the folder size stopped increasing but the process kept running, no memory was released, and CPU was still at 100% (all according to htop ). The loading process is single threaded, only the JVM is using more than 1 thread - I guess by the ParallelGC . I'm not sure how to diagnose this type of problem but was instructed to try jstack , so have included its output below. Anyone

deadlock on a single SQL Server table

由 巧了我就是萌 提交于 2019-12-06 01:03:10
I am using SQL Server 2008 Enterprise. And using ADO.Net + C# + .Net 3.5 + ASP.Net as client to access database. When I access SQL Server 2008 tables, I always invoke stored procedure from my C# + ADO.Net code. I have 3 operations on table FooTable. And Multiple connections will execute them at the same time in sequences, i.e. executes delete, the execute insert and then execute select. Each statement (delete/insert/select) is of a separate individual transaction in the single store procedure. My question is whether it is possible that deadlock will occur on delete statement? My guess is

Deadlock Delphi explanation/solution

由 血红的双手。 提交于 2019-12-06 00:54:49
问题 On a server application we have the following: A class called a JobManager that is a singleton. Another class, the Scheduler, that keeps checking if it is time to add any sort of job to the JobManager. When it is time to do so, the Scheduler do something like: TJobManager.Singleton.NewJobItem(parameterlist goes here...); At the same time, on the client application, the user do something that generates a call to the server. Internally, the server sends a message to itself, and one of the

How does this recursive synchronized call not deadlock?

由 左心房为你撑大大i 提交于 2019-12-05 23:30:50
I have a set of methods that all synchronize to the class object (can't use self, because multiple instances of this object could be used in multiple threads). Some of those methods call other methods in the class that also synchronize on the class object. Somehow this works and does not cause the deadlock I would expect it to. I would assume that testA would be blocked from running because testB already has a lock on the class object, but this apparently isn't the case. Is it something special that @synchronized is doing or is this a feature of the underlying mutex locks? Example code that

How to detect and find out a program is in deadlock?

由 房东的猫 提交于 2019-12-05 23:02:12
问题 This is an interview question. How to detect and find out if a program is in deadlock? Are there some tools that can be used to do that on Linux/Unix systems? My idea: If a program makes no progress and its status is running, it is deadlock. But, other reasons can also cause this problem. Open source tools are valgrind (halgrind) can do that. Right? 回答1: I would suggest you look at Helgrind: a thread error detector. The simplest example of such a problem is as follows. Imagine some shared
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