Locking allows different types of resources to be locked by a transaction.
0
votes
0answers
6 views
Robustly send notifications from multiple processes
We have Notifications stored in a notifications table, which is worked on by multiple background workers. The notifications table has these relevant attributes:
id (primary key, unique)
send_at ...
3
votes
1answer
46 views
Queuing web service calls
Every call to the web service goes through a custom queuing system. This has a limit that is set to 1. Every call that enters the same time with another call is purged and not handled. Not sure if ...
0
votes
1answer
43 views
Unlocking spreadsheet files quickly - follow-up
I recently posted a program I made to unlock spreadsheet files( see also ), I've taken all of your advice and made it more Ruby like, it has no shell commands in it, and uses ...
4
votes
1answer
62 views
Unlocking spreadsheet files quickly
I've created a program for my job that unlocks spreadsheet files quickly and efficiently. What we use to have to do before this program is we'd have to go into the system, search for the file, kill ...
4
votes
2answers
102 views
Parallel foreach with configurable level of concurrency
The purpose of this code is to let me loop over 100 items (up to MAX_CONCURRENT at a time), performing some action on them, and then return only once all items have ...
2
votes
1answer
56 views
New caching and deferred evaluation strategy
This is a simple wrapper class for a lambda expression, that stores one as Expression and hands it back out either as ...
5
votes
1answer
58 views
Lock implementation using atomics
I was recently given an interview and was asked to write my own lock implementation using atomics, but not necessary reentrant.
I didn't answer the question, but at home, I wrote this code. Please ...
5
votes
2answers
1k views
Locking mechanism in C#
I would like you to review the locking mechanism I implement in C# class. Will it be working correctly with many threads?
Please don't mind rest of the code because I just try to repair the class ...
6
votes
2answers
105 views
Item-level locks for a large number of items
Background
I'm working on a system that records information about a large number of external documents. These documents are organized by "repository". There can be a modest number of repositories ...
0
votes
0answers
97 views
Simple distributed lock manager server based on zmq
I wrote a simple server to distribute locks on a network. It is used in a multi-server environment with a shared home directory to secure non-multiprocessing safe file writing (...
2
votes
1answer
43 views
-2
votes
2answers
443 views
2
votes
1answer
66 views
Thread-safe removewhere
I'm trying to implement a HashSet that it's accessed from different thread for querying, adding or deleting elements. It doesn't make sense to use a Dictionary for I got several search keys so I won't ...
7
votes
2answers
581 views
Spinlock for C++ kernel (with x86 ASM)
This is some prototype code for a spin-lock for my toy operating system. Bear in mind this means there are no standard library routines to fall back on. It's also for C++11 compilation and will only ...
4
votes
2answers
198 views
Generic object pool class using Spinlock/Monitor
I've written the following object pool class, and because this is my first encounter with synchronization primitives, I need reinsurance from an expert that this code is safe. I've tested it myself ...
4
votes
1answer
1k views
Async distributed locking with StackExchange.Redis [closed]
I have been trying to write an analogy to this approach to distributed locking with two differences:
making it asynchronous
making it work with StackExchange.Redis rather than AppFabric Cache.
My ...
0
votes
1answer
136 views
Thread lock algorithm [closed]
I am trying to make a thread lock for a method so that only one thread can run it at a time. Although this is a well known issue and in C# there is the lock keyword to do it. I was trying to do it on ...
5
votes
1answer
42 views
Simple file locking wrapper command in C
A simple command that wraps another command, locking a file first. It is similar to flock, just simpler.
...
4
votes
3answers
565 views
Using goto to wait on the result of a database query to change
This is a small personal project where most non-sensitive data is distributed to some globally hosted CDN servers, which store the JSON. Now one problem we've seen during testing is a few deadlocks ...
6
votes
1answer
170 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. As such, we have attempted to implement code that would prevent them from causing bad things to happen.
This ...
5
votes
2answers
299 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
883 views
Reading a line of text from a socket
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 me one way or another to comment, but I have a hard time with ...
7
votes
1answer
313 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
126 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:
...
4
votes
1answer
2k 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
293 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 ...
5
votes
1answer
124 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
36 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
119 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
955 views
Portable C++ boost::interprocess::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
196 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 ...
3
votes
1answer
367 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
2k 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
680 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 ...
3
votes
1answer
130 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
190 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
213 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
207 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
165 views
Lock for preventing concurrent access in client data - follow-up
This is a follow-up to: Lock for preventing concurrent access in client data
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.
...
1
vote
0answers
156 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
529 views
Thread-safe session manager
Expected behavior of the code below:
There will be one static SessionManager accessed by many threads.
Multiple calls to ...
6
votes
3answers
147 views
Thread-safe retirement account class
Are these classes properly guarded for thread safety? Do you see any issues with any of the classes?
...
5
votes
1answer
627 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
398 views
Python app-level document/record locking (eg. for MongoDB)
MongoDB does not provide means to lock a document (like SELECT FOR UPDATE in RDBMS).
There is a recommended approach to Isolate Sequence of Operations, which is ...
2
votes
1answer
390 views
RAII-style lockable objects
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.
I am working on a Windows project ...
2
votes
2answers
402 views
File locking between server threads
I have written the below code where the server is getting requests from clients on a socket and creating a thread per client. Each client thread is then writing to a file which is common to all the ...
6
votes
1answer
2k 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
604 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
84 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
322 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 ...
