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Questions tagged [concurrency]

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I am using a GCP instance and would be connecting to it using SSH

I would like to run 2 commands that need to run simultaneously. How Can I acheive this ? Command1: $ socket -s /home/dc-host/data/monitor Command 2: $ bash startvm.sh
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-1 votes
2 answers
458 views

What is going on when multiple requests are made to a host?

This is a very basic question about the mechanics of computers. What are some of the common ways that a host handles multiple requests during the code execution phase for applications with millions of ...
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4 votes
1 answer
12k views

How can I tell the maximum threads my server can run?

Here is the machine spec: CPU(s): 20 Thread(s) per core: 1 Core(s) per socket: 10 Socket(s): 2 Based on what I've read so far, these numbers mean that I can run 20 ...
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  • 143
0 votes
1 answer
24 views

Safely update configuration file stored on NFSv3 mount

I have a configuration file config_file that is stored on an NFSv3 network mount, and I would like to update that file safely. Here are the conditions and restrictions that I'm working under: There ...
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1 vote
1 answer
372 views

SQLite WAL concurrent write performance on UNIX systems

I have two setups: one runs on windows 10 (ntfs partition), the other on debian (ext4 partition). The R source code is the same. The main process starts 8 child-processes (P-SOCKS) -- on 8 vcores -- ...
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0 votes
1 answer
58 views

How to allow concurrent execution of job arrays with job share (-js)

I'm trying to have SGE run job array tasks concurrently based on the job shares parameter of qsub but it seems not to be working as expected. Is there a way to enable concurrent task execution based ...
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  • 417
1 vote
2 answers
968 views

AWS codedeploy: parallel or concurrent deployments

I'm currently experimenting with AWS codedeploy and noticed that there can be only one deployment running at the same time. I have six applications (in the AWS codedeploy sense) each with one ...
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  • 121
0 votes
1 answer
265 views

Does the maximum amount of open descriptors in a server include it's children?

I know that Linux limits the maximum amount of open descriptors, usually to 1024. Now say I need to create a server which will handle more than 1024 users, 2000 for example, without tampering with the ...
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2 votes
1 answer
1k views

Gunicorn does not repondes more than 6 requests at a time

To give you some context: I have two server environments running the same app. The first, which I intend to abandon, is a Standard Google App Engine environment that has many limitations. The second ...
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  • 193
0 votes
4 answers
98 views

Tips on technology for one program, many concurrent http clients on small host? [closed]

What technology could be used for one application to serve many simultaneous users on a small resource-constrained host (eg: Rasbperry Pi or similar)? That is, it doesn't need a general purpose web ...
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  • 109
1 vote
0 answers
225 views

Understanding clients-server max-concurrent-connections and TIME_WAIT state

I know there are a lot of questions and also answers around the TIME_WAIT state of a socket connection, but somehow non of them (or maybe from an experts perspective all of them) help me to understand ...
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  • 111
2 votes
1 answer
589 views

Google Cloud SQL / App Engine concurrency limits

I've been using Google App Engine to host my APIs and keep banging up against the limitation of concurrent database connections. The docs say that you can only have up to 12 concurrent connections per ...
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  • 21
4 votes
1 answer
2k views

How to circumvent siege concurrency socket select timed out

Being trying to test load capacity of a web site. I am using an aws ubuntu xenial server t2.micro as test client and have SIEGE 3.0.8 and apache benchmark Version 2.3 while ab -c 100 -n 100000 url ...
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1 vote
1 answer
649 views

Terminal Command to find maximum allowed TCP/IP connection on a port in Apache server(CentOS)

Is there any terminal commands to check the maximum allowed number of concurrent TCP/IP connections can be done in Apache server with CentOS??
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0 votes
1 answer
4k views

Is it advised to close MySQL connection after every query

I have some sort of web crawler with PHP, which crawls the web and stores information about the pages in the database, now the thing is, loading pages takes a lot of time, and on top of that my script ...
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2 votes
0 answers
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How does a server (e.g. web) manage multiple request/connections? [closed]

I read that apache has a solution to create new thread per new request, but I still have some questions. How is possible that one server can manage thousands (even a milion connection - depends from ...
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0 votes
1 answer
119 views

Apache delays serving an empty html file while processing a concurrent request

I have a website, which queries a Varnish server, which queries an Apache server, which queries a db server. At 07:00:00, a request is send to the Apache server, which triggers a db request that ...
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  • 217
-4 votes
1 answer
1k views

What is the internet Bandwidth needed to support 2000 concurrent requests?

For one our projects, we need to calculate the internet bandwidth required to support 2000 concurrent requests/per second. Following is the scenario detail: If 1 user accesses the page, the ...
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1 vote
3 answers
1k views

Why is method that uses gevent in a mod_wsgi deployed Flask api raising error about switching threads?

I am trying to deploy a Flask api via Apache/mod_wsgi. The api uses Gevent to provide concurrency for a recursive method. However, it is throwing the following error [Mon Feb 08 12:05:37 2016] [error]...
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2 votes
2 answers
3k views

Postfix - rate limit outgoing concurrent connections to one machine/ip

I need to limit postfix outgoing connections for specific mailservers, but it seems to me that posfix's limiting is based on domains? What if there is one mailserver for more domains? I tried to find ...
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  • 19
7 votes
1 answer
14k views

How to allow more than two simultanous sessions on Azure

One of our servers is on Azure and we are remotely connecting to it. Unfortunately Azure allows only two users to be logged in at the same time. When the third user tries to log in, he is given the ...
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  • 261
4 votes
1 answer
16k views

Limit concurrent connections to Postfix server

I'm having trouble limiting the number of concurrent connections from the same client to my Postfix server. Limiting the maximal number of concurrent processes, from the same or different clients, is ...
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  • 141
0 votes
1 answer
505 views

Server is not responding when single connection is blocked

I'm not sure how to properly specify this problem, I'm not really a server expert. I will be glad to provide additional data on demand. I have a PHP web-application running on Ubuntu Server with ...
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0 votes
1 answer
147 views

Excel 2013 Power Pivot RemoteApp - limited by 4 concurrent users? [closed]

We're trying to use Excel 2013 (64bit) + Power Pivot via RemoteApp. The problem we're having is basically the same as described this TechNet thread. 4 concurrent users have no problem using Power ...
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0 votes
0 answers
590 views

xmpp openfire connection manager not working

I have downloaded the connection manager here .In windows I have extracted it to program files in C drive and edit the conf/manager.xml to set domain and password. I also enabled connection manager in ...
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  • 101
3 votes
1 answer
422 views

apache mpm_worker server failed to respond

I'm trying to update our current Apache 2.4.9 configuration from using prefork to worker mpm. I'm doing some simple load testing using jmeter to compare the performance between the 2. My first test is ...
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0 votes
1 answer
2k views

Apache httpd response time increase with concurrent connections

I know many questions have been asked on this subject, but I didn't find an answer to help me. I'm trying to have Apache httpd answer 200 concurrent connections. I'm testing with jMeter, fetching a ...
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  • 171
0 votes
1 answer
2k views

Ask nginx to handle requests from the same IP in parallel?

I have an application internal to my company that needs to be very fast per client, because the clients are so limited and the whole thing is internal. So, the client is expected to send so many ...
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1 vote
1 answer
362 views

Throttling a user across multiple datacenters

I'm trying to implement a throttling feature on nginx, that is shared across multiple servers across multiple datacenters. I would like to know what would be the best practice for building this. For ...
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  • 442
2 votes
1 answer
3k views

Server's maxconn parameter in haproxy

I'm using HAProxy in production to balance queries to a series of server instances that can only process 1 query at a time (by our own decision). Knowing that I set the maxconn parameter in the server ...
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  • 121
2 votes
2 answers
4k views

How to determine POSIX advisory file locks are working in simfs in the VM I'm using?

I'm looking for a command-line utility or some other way to test effectiveness of file locks, specifically POSIX advisory locks (which aren't only for POSIX, btw) in a Linux filesystem. Specifically, ...
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2 votes
2 answers
18k views

How does server handle multiple clients on the same port? Multiple sockets or multiple ports? [closed]

I have a misundertanding about some networking theory and because I couldn't find a definitive answer online (most resourceas are theory and theory etc without concise examples) I'm asking here. ...
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2 votes
1 answer
512 views

Plotted ab results of node, cluster and nginx, odd results?

I did a test with ab -n 10000 -c 1000 against node.js with different configurations, each returning the string Hello World!. Results seems odd to me. X axis is the number of requests, y is the ...
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  • 325
1 vote
0 answers
274 views

Fail with ab test with nginx, two workers and 1024 connections?

I'm doing some tests with nginx 1.4.1 and Node.js 0.10.5 on my development machine (P8700 Dual Core 2.53Ghz, 4Gb RAM running Xubuntu x64). Unfortunately I can't do ab with 100000 requests with a ...
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  • 325
4 votes
2 answers
686 views

How to lock concurrent access to a shared webservice from multiple webservers?

Our production environment consists in n Apache web servers accessed by browsers via a frontal load balancer. Very typical. 99% of our HTTP requests are gracefully handled by this parallelized ...
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  • 205
0 votes
1 answer
1k views

iSCSI and NFS file locking and concurrency

I've got a linux host that need to mount a data share located on a NAS. The choice is between NFS v3 (NAS limitation) and iSCSI. The initial idea was to have a NFS mount to the file server that ...
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  • 105
1 vote
3 answers
2k views

Several Cron at same minute

I'm installing a bunch of Magento shops on a webserver. Every website has a cron job that Magento uses to update its stuff -- it takes 3-4 seconds to complete. The instructions tell to set it to run ...
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  • 143
0 votes
1 answer
9k views

Optimizing Apache for large concurrent requests and static files

OK, I know I'm asking a question that's been asked multiple times before (e.g. here - Serve millions of concurrent connections and static files?) but there appears to be no concrete solutions, so I ...
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  • 587
0 votes
3 answers
87 views

What framework is good for delivering data that is commonly changed in a few second and is assessed by lots of people (similar to stock quote)? [closed]

I am only familiar with php and javascript and I guess php is not good at serving large amount of concurrent request. I would be grateful if someone can introduce me to more appropriate framework for ...
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  • 231
3 votes
2 answers
7k views

Heavy write to Galera cluster - table locked, cluster practically unusable

I set up Galera Cluster on 3 nodes. It works perfectly for reading data. I have done simple application to make some test on the cluster. Unfortunately I have to say that the Cluster fails totally ...
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  • 333
3 votes
1 answer
1k views

Apache Benchmark is slow from public network, magnitudes faster locally. What are some things I do to speed this up?

I am testing my Linode Ubuntu 14 64bit server out, it's the most basic server available from them. I am using Apache Benchmark to test the server, as well as a multithreaded script I wrote in Python, ...
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  • 365
0 votes
2 answers
425 views

Simulating 1000 concurrent downloads

I'd like to simulate 1000 concurrent downloads of a single file from Cloudfront. I figured I'd setup ~10-20 xlarge EC2 instances for this. Is there an obvious way I'm missing to trigger this at the ...
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  • 1,110
3 votes
2 answers
8k views

Tracking down "Connection reset" errors in Linux

I'm handling large numbers of concurrent downloads (approx. 500 per server) using Java. All the files are being downloaded from Amazon S3, and the downloading server is an EC2 m1.large instance. ...
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  • 233
13 votes
5 answers
25k views

NGINX timeout after +200 concurrent connections

This is my nginx.conf (I've updated config to make sure that there is no PHP involved or any other bottlenecks): user nginx; worker_processes 4; worker_rlimit_nofile 10240; pid ...
0 votes
1 answer
2k views

How do concurrent filesystems work? [closed]

From learning about how filesystems use transactions and logs to make sure that the disk is in an atomic state even after there's been a system crash, I've become curious about how filesystems deal ...
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0 votes
1 answer
256 views

How do i get concurrent asp.net on linux?

-edit2- It turns out asp.net (i dont know if its mono specific) blocks if the url and ip address are the same. Its nonblocking if i run it from my local machine and server at the same time. I have ...
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2 votes
1 answer
219 views

IIS 7.5 on Windows 7 Ultimate

I am looking to install Windows 7 Ultimate and run IIS 7.5 on it. However, I would like to know exactly what my limitations will be with this setup. While researching this topic various resources ...
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1 vote
0 answers
1k views

tomcat max number of threads

I have a very confusing scenario.. We are using tomcat6 to host an internal application. In server.xml file maxthreads attributes is set to 150 but if I log on to the manager, in "http-8080" section I ...
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0 votes
1 answer
866 views

postfix concurrency limit with round robin dns

Take the following internal round robin dns setup mymta.com. IN A 172.31.1.1 mymta.com. IN A 172.31.1.2 mymta.com. IN A 172.31.1.3 mymta.com. IN A 172.31.1.4 mymta.com. IN A 172.31.1.5 mymta.com. IN ...
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  • 151
0 votes
1 answer
547 views

Limit on concurrent connections: Determined by webserver or database?

Does the webserver or is it the database that limits the number of concurrent connections?
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  • 993