Locking allows different types of resources to be locked by a transaction.
3
votes
0answers
55 views
Deadlock watchdog in a server to defend against poorly written extensions
In the Red5 server we have no control over what implementers do with their applications and as such we have attempted to implement code that would prevent them from causing bad things to happen.
...
5
votes
2answers
79 views
Generic Object Pool in C#
I have a limit of 100 sessions (each session held in an object). Many threads will be requesting sessions, and it is very possible that all 100 sessions could be in use at any time.
I'm a Junior ...
7
votes
6answers
678 views
Reading a line of text from a socket
I'm hoping this is useful for other people, and not just me.
I tend to write code, with very few comments, and few line breaks. I'm currently just a student at a University. I've had professors tell ...
6
votes
0answers
65 views
Simple, encapsulated C++ logger that can deal with fork/exec situations
Motivation: for whatever reason, some of the available 3rd party logging libraries don't really deal with programs that get fork'ed/exectuted well. For instance, ...
3
votes
2answers
63 views
Locking a remote file
I am using Java to modify remote files in different machines by ssh. At the same time, only one thread is allowed to modify the file in one machine.
I implement the logic like this:
...
1
vote
1answer
99 views
Monitoring progress in Parallel.ForEach every minute
I'm using Parallel.ForEach to download 500K URLs and I want to monitor the number of URLs that have been successfully downloaded each minute.
...
10
votes
2answers
157 views
RAII Pattern for Downgradable ReadWriteLock
The example for downgrading ReentrantReadWriteLock in the Java documentation seems really unsafe when handling exceptions. I tried to write a simple class to simplify it. Do you see any cases where it ...
5
votes
1answer
82 views
Is my spin-lock implementation correct?
I'm working on a project where a spinlock is more appropriate than a mutex, and after few tries I came up with:
...
3
votes
1answer
30 views
Good approach to raise an exception
I have class House and module Lockable. Locking and unlocking House should reflect the real ...
1
vote
2answers
81 views
SynchronizedArrayList implemented using reader writer synchronization
I am trying to understand the workings of reader writer locks. For the sake of learning, I implemented reader writer synchronization by my own. I implemented ...
7
votes
1answer
341 views
Portable C++ boost::iterprocess::mutex
I was looking for long time around to have a portable robust solution for multiprocessing synchronization. Who touche this things know that good solution are boost::iterprocess named sync objects.
...
1
vote
0answers
101 views
Lock a process in PHP
We had a situation where it was necessary that a script only be running in one process at a time.
The solution was to make a "LockByProcess" class that checks a database for an existing process, and ...
2
votes
1answer
128 views
Mutualising multi-threaded calls to EJB from Servlet
I have a Servlet that makes an EJB call to a backing server which takes about a second to return some data that changes reasonably regularly.
I can't cache the data on the servlet-side, so I have ...
7
votes
2answers
941 views
A simple semaphore in Java
It is a simple semaphore in Java. Although it passes all their tests with flying colors, I'm still not sure it's correct.
For example, the last thing I wasn't sure about was ...
3
votes
2answers
440 views
Prevent re-entrant function call in C++
The purpose of this is to prevent a re-entrant function call in a single thread, e.g. prevent the situation where func() calls ...
1
vote
0answers
54 views
Moonshot & `Thread.Abort` - dealing with the fallout
Recently, I encountered an anomaly in the manner by which a worker thread was terminated. It prompted me to do some searching and I realized that I was constructing thread code in a haphazard manner. ...
3
votes
1answer
97 views
Social Share count
I am creating a social sharing counter plugin for my WordPress blog. I want to fetch the counts of number of likes, shares, Facebook comments (I am using Facebook comment box), twitter tweet counts ...
2
votes
1answer
97 views
Testing Promises vs Lock performance
I'm not sure if my lock usage is correct and safe. I wanted to know what will be best approach to deal with situation when one thread have to wait for being initialized by another so I written this ...
5
votes
1answer
124 views
Using CountDownLatch for blocking the reads if writes are happening
I am trying to implement lock by which I want to avoid reads from happening whenever I am doing a write on my three maps.
Requirements:
Reads block until all three maps have been set for the first ...
4
votes
1answer
119 views
How to avoid reads before initialization is complete and return updated set of maps value?
This is a follow on to: How to prevent reads before initialization is complete?
I am trying to implement lock by which I want to avoid reads from happening whenever I am doing a write on my three ...
1
vote
0answers
73 views
Reliability of flock mutex (LOCK_EX|LOCK_NB)
I would like to test reliability of system flock in a multi-threaded and concurrent environment as some suggest that they are not reliable (in comments).
Thus I ...
11
votes
2answers
228 views
Is this use of a resource based on session ids thread safe?
Let me first describe the expected behavior of the code below:
There will be one static SessionManager accessed by many threads.
Multiple calls to ...
5
votes
3answers
127 views
Feedback on thread safety of the classes
I have following classes. Are they properly guarded for thread safety? Do you see any issues with any of the classes?
...
5
votes
1answer
112 views
Operations on files and their locks - code too bulky?
A couple of hours ago I asked a question on Stackoverflow to find out if there is a good way to delete files in a folder only if all files are indeed deletable and I got some good answers that led me ...
2
votes
0answers
215 views
Python app-level document/record locking (eg. for MongoDB)
Introduction
MongoDB does not provide means to lock a document (like SELECT FOR UPDATE in RDBMS).
There is recommended approach to Isolate Sequence of Operations, which is sometimes called ...
2
votes
1answer
192 views
RAII-Style Lockable Objects
TL;DR: Without the phrases "use Boost" and "use C++11", does the posted code for RAII-style locking of a resource look correct and safe, or is there something I've missed.
Long Version:
I am working ...
1
vote
1answer
222 views
C: File locking between server threads
I have written below code where the server is getting requests from clients on socket and creating a thread per client. Each client thread is then writing to a file which is common to all the threads. ...
4
votes
1answer
899 views
Locking during cache population
Here I want to lock when populating a particular cache object, without blocking other calls to the same method requesting Foos for other ...
1
vote
1answer
330 views
Loading data async with queue. Proper write only locking and scheduling
I have to store and return data on multitasking requests. If data is missing, I schedule loading and return null. I'm using some nubie scheduling by saving current jobs in a list. Also I need data ...
0
votes
2answers
82 views
Is this a good way of handling item reservations?
I have a site were we sell unique items. When a user clicks to buy an item we have to reserve it. This prevents other buyers from purchasing the item while the first buyer is checking out.
When a ...
4
votes
1answer
193 views
Is this the best message delay algorithm?
In my application I am attempting to queue outgoing messages by the following rules
By default they should be sent no less than messageDelay apart
Some messages ...
1
vote
4answers
441 views
Simple multi-threading class: Does anybody spot potential lock-based concurrency issues?
Trying to write a multi-threaded utility that logs some audit trails to the DB every 30 minutes, or whenever my storage data structure (a list in this case) exceeds a certain limit. The code works ...
7
votes
3answers
7k views
Dining philosophers problem with mutexes
I know this dining philosophers problem has been researched a lot and there are resources everywhere. But I wrote a simple code to solve this problem with C and then turned to Internet to see if it's ...
1
vote
2answers
4k views
Static class ThreadPool implementation
The following code is a self-implementation of the static class ThreadPool in C#, only the QueueUserWorkItem (the simpler ...
2
votes
4answers
4k views
Designing a better logger class
Could you please critisize the logger class below? Can it be used in a multi threaded web environment? If not how can I improve it? Is there anything wrong with locking in WriteToLog method or ...
1
vote
3answers
82 views
How to correctly get a IDisposeable when you need to lock the factory?
If I need to create a IDisposeable object from a factory, but if the factory object is not thread safe and requires me to lock on it is this the correct pattern to use?
...
4
votes
2answers
148 views
Getting a decryptor object
I need to lock on my AesManaged instance _Aes to call CreateDecryptor() however the CreateDecryptor() method is not thread safe and this function could be called by ...
7
votes
2answers
326 views
Synced/Atomic access
Forward
I would love any comments you have, any ideas, any flaws you can find, and any suggestions you might have regarding the code below.
If this is similar to other implementations, I would love ...
3
votes
1answer
1k views
Resource Pool implementation with ReentrantLock and Condition
The Resource Pool is similar to the implementation of a semaphore. It takes the class type of the resource and number of resource pools associated with it as the constructor parameters. There is a ...
1
vote
2answers
2k views
Multithreading concepts with Producer Consumer
I just wanted to confirm if this example I created would qualify as a good example of a multithreaded producer consumer. I would like any review changes on improving this example. I found that static ...
3
votes
4answers
1k views
Java Non Reentrant Lock Implementation
I have implemented a Non Reentrant Lock. I want to know if this has any mistakes, race conditions etc. I am aware of the fact that existing libraries have to be used (instead of writing our own), but ...
6
votes
0answers
197 views
Concurrency limit map in Go
Please someone who knows locks, mutexes, and Go, review the following code.
Task: per host concurrency limits for web crawler (map[string]Semaphore).
I considered chan struct{} (chan bool) approach, ...
4
votes
1answer
191 views
Improving handling of data structure used in parallel
I have a class extending the Dictionary class. This class is used for storing some information (modeled in CustomClass) and accessing it through an integer ID.
To ...
10
votes
4answers
1k views
Force locking for thread-safety
After reading Herb Sutter's Associate Mutexes with Data to Prevent Races, I found that my solution was superior in several aspects, least important first:
The code is cleaner, without macros
No ...
2
votes
1answer
501 views
Mutex implementation for uniprocessor bare metal embedded OS
I wrote this recently for one of my projects, any error you guys can spot or a feature which could be implemented without eating up resources or some optimisations ? Oh and it isn't meant for Multi ...
3
votes
4answers
269 views
Configurable synchronization approach in Java
I am interested in the community opinion about the following approach for the synchronization.
Generally it is based on the idea to have a configurable way to apply locking on some logic parts.
Any ...
1
vote
2answers
1k views
ReentrantReadWriteLock lock upgrade method
I have a question about lock upgrading.Specifically what bothers me is between readlock.unlock() and following writelock.lock()...
I am providing a nearly complete implementation for a sample cache.I ...
2
votes
1answer
307 views
std::lock implementation in C with pthreads
I messed a little bit with pthreads and needed an alternative to the C++11 function std::lock (2 args are enough), and this is what I came up with:
...
2
votes
1answer
1k views
ReentrantLock with priorities for waiting threads
I am trying to have a ReentrantLock with another way to determinate which thread will have the lock in the waiting queue. ...
4
votes
2answers
4k views
Did I need to use lock to ensure that Queue.Dequeue is Thread Safe in this case on .NET 2.0?
Is this ok? I am using C# and .NET 2.0
I have this Queue declared in my class :
...
