Increase number of TCP connections

I'm running some sample connection tests with node.js and the sample test is one that creates a number of connections to a node.js server.
I cannot get above 249 connections on a specified port and I'm wondering how / if I can increase this number.
1) Can someone describe or point me to a document that will educate me on how to change this configuration in OSX?

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Similar Messages

How to limit the number of TCP connections beeing used concurrently while a page is beeing loaded?

We manufacture industrial small-footprint control modules with embedded web server. The resources of these modules are very limited, especially in RAM. We have problem, that FF opens 15 parallel TCP connections while loading a web page (main html page first, then all icons simultaneously). We can not handle such behavior because of lack of RAM memory needed for TCP buffers.
Question is how to limit the number of concurrent TCP connections the browser will use? We need to do it somehow directly from the page, we can not push our customers to change the general settings of their browsers (they would not understand such things anyway).
Do anyone have any suggestion?

Sorry, one other thought. Many web designers now combine all icons into a single image and use CSS to clip the image so that only the desired portion is displayed. This minimizes the number of required connections and increases the probability that the image can be retrieved from cache.
More info:
* [http://www.w3schools.com/css/css_image_sprites.asp CSS Image Sprites - W3Schools]
* [http://www.alistapart.com/articles/sprites/ A List Apart: Articles: CSS Sprites: Image Slicing’s Kiss of Death]
* [http://coding.smashingmagazine.com/2009/04/27/the-mystery-of-css-sprites-techniques-tools-and-tutorials/ The Mystery Of CSS Sprites: Techniques, Tools And Tutorials | Smashing Coding]
No idea whether this is practical for your application.

Max number of TCP connections to one IP?

Is there any limit, imposed by the TCP protocol, to the number of active connections to one IP address on one interface?
I'm asking this because it's easy to add more servers behind a load balancer, but I wonder if the TCP protocol limits in some fundamental way the number of connections to the load balancer itself.
Let's say there's an ACE 4710 load balancer in front of a bunch of Web servers. The balancer exposes one IP address to the clients on the public network. The connections are forwarded to the Web servers on the private network. The balancer is also doing NAT: the servers see the connections originating on a private IP on the load balancer.
On the client side, each connection is uniquely identified by the quartet (source IP, source port, dest IP, dest port). So as long as each client only creates one connection, I think the limit here is just the amount of RAM on the load balancer.
On the server side, same thing, each connection is identified by the same quartet, so I guess the theoretical limit here is 64k connections per server, due to the limit imposed by the source port numbers on the load balancer.
OTOH, if the load balancer is not doing NAT (the servers see the connections originating on the public IPs of the clients), then there should be no limit imposed by the TCP protocol.
Is that right? Comments?

you got it right.
Gilles.

HTTP tunneling / number of TCP connections

Environment WLS 7.0 Sp2
We are experimenting with http tunneling and we noticed the following behavior,
when performing a lookup to get a handle to a few session beans that our UI is
using, Weblogic opens an additional TCP connection for every lookup however when
using t3 Weblogic opens a single connection for all of them. Our guess is that
Weblogic's T3 is optimized to pipeline and multiplex everything asynchronously
over one TCP connection.
Is there a way to configure Weblogic to use a single TCP connection when tunneling?

I believe it would just be an OS-level limit, on the number of socket handles that can be opened.

WLS 8.1SP4 and the ever-increasing number of JMS connections

We are running a CRM application on a BEA WebLogic 8.1SP4 cluster and we are experiencing some regular performance problems.
When looking at the active JMS connections we see that they can increase till 800 current connections until the application slows down. It takes a very long time to generate the active JMS connections overview
The current number of connections is always nearly identical to the connections high value.
Do you maybe recognize this kind of behavior? Your comments, advice or suggestions are very much appreciated.
With kind regards,
Fred

We are running a CRM application on a BEA WebLogic 8.1SP4 cluster and we are experiencing some regular performance problems.
When looking at the active JMS connections we see that they can increase till 800 current connections until the application slows down. It takes a very long time to generate the active JMS connections overview
The current number of connections is always nearly identical to the connections high value.
Do you maybe recognize this kind of behavior? Your comments, advice or suggestions are very much appreciated.
With kind regards,
Fred

How can I increase number of devices connected to Fusion wifi

When adding a fifth device my printer is knocked off

If you look in the Misc. Digital Group you'll find a Family called TIL (Technology Independent Logic). This family is most similar to V5.12. You'll find a 7-1 NAND gate in there.
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WAAS - TCP Connection High-Water Mark

Is there a way to tell the historical statistic for maximum number of TCP connections in a WAE? We are in the middle of a deployment and I am wondering how well we sized our HQ cluster.

Through CM dashboard -> manage devices and go to edge or core device, you will be able to see the connections for each device.
The other option, is to check and see if you are seeing a lot of bypass traffic.
Once WAAS reaches max, traffic will be bypassed until max sessions drops

TCP connection error when sending MODBUS commands to WAGO 750-881 controller after 113655 bytes of data have been sent

Hi all,
I am new to the world of labview and am attempting to build a VI which sends commands to a 750-881 WAGO controller at periodic intervals of 10ms.
To set each of the DO's of the WAGO at once I therefore attempt to send the Modbus fc15 command every 10ms using the standard Labview TCP write module.
When I run the VI it works for about a minute before I recieve an Error 56 message telling me the TCP connection has timed out. Thinking this strange, I decided to record the number of bytes sent via the TCP connection whilst running the program. In doing so I noticed that the connection broke after exactly 113655 Bytes of data had been sent each time.
Thinking that I may have been sending too many messages I increased the While-loop delay from 10ms to 20, 100 and 200 ms but the error remained. I also tried playing with the TCP connection timeout and the TCP write timeout but neither of these had any effect on the problem.
I cannot see why this error is occuring, as the program works perfectly up untill the 113655 Bytes mark.
I have attached a screenshot of the basic VI (simply showing a MODBUS command being sent every second) and of a more advanced VI (where I am able to control each DO of the WAGO manually by setting a frequency at which the DO should switch between ON and OFF).
If anybody has any ideas on where the problems lie, or what I could do to further debug the program this would be greatly appreciated.
Solved!
Go to Solution.
Attachments:
Basic_VI.png ‏84 KB
Expanded_VI.png ‏89 KB

AvdLinden wrote:
Hi ThiCop,
Yes the error occurs after exactly 113655 bytes every time. The timeout control I would like to use is 10ms, however even increasing this to 1s or 10s does not remove the error, which leads me to believe that this is not the issue (furthermore, not adding any delay to the while loop, thus letting it run at maximum speed, has shown that the TCP connection is able to send all 113655 bytes in under 3 seconds again pointing towards the timeout control not being the issue here).
I attempted Marco's suggestion but an having difficulty translating the string returned into a readable string, (rightnow the response given is " -# + ").
As to your second suggestion, I implemented something similar where I created a sub VI to build a TCP connection, send a message and then close the connection. I now build each message and then send the string to this subVI which successfully sends the command to my application. Whilst not being the most elegant method of solving the issue, it has resolved the timeout problem meaning I am able to send as many commands as I want. So in that sense the problem has been solved.
If you still have tips on how to correctly read the TCP read output, I would however like to see if I could not get my first program to work as it is slightly more robust in terms of timing.
Modbus TCP RTU is a binary protocol, as you show in your Basic VI, where you format the data stream using byte values. So you have to interprete the returned answer accordingly with the Modbus RTU spec in hand. Now what is most likely happening is that the connection gets hung after a while since you do NOT read the data the device sends as response to your commands. The TCP/IP stack buffers those bytes and at some point the internal buffers overflow and the connection is blocked by the stack. So adding the TCP Read at strategic places (usually after each write) is the proper solution for this. Is there any reason that you didn't use the NI provided Modbus TCP library?
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Established tcp connection of question

Now we have two Master LDAP server, A and B. Both of them have Replication function on.
I have encountered a problem. There are always a lot of Established tcp connection between them. Once they established this kind of tcp connection, it will never be closed and keep on increasing the connection number. This will lead LDAP A daemon become a zombie daemon so that it cannot supply the LDAP service. At this time, server A usually has a very high load. After rebooting server B, we use the following command to test server A. It turns out that the connection between this two server is still established and never be closed.
Restart Sever A ldap daemon can temporarily solve this problem. But it will repeat the above situation about one week later.
We feel very frustrated about this problem. My question is how to close this kind of tcp connection or do you have any resolution about our problem.
Thank you.
bash-2.05# netstat -an|grep 192.168.1.92
192.168.1.91.389 192.168.1.92.61206 49680 0 49680 0 ESTABLISHED
192.168.1.91.389 192.168.1.92.61207 49680 0 49680 0 ESTABLISHED
192.168.1.91.389 192.168.1.92.61212 49680 0 49680 0 ESTABLISHED
bash-2.05# netstat -an|grep 192.168.1.92|wc -l
1667

You may want to send this info directly to Apple at http://www.apple.com/feedback/iphone.html as in here, we are just users so really cannot offer any help to how the iPhone is coded to work.

ASA 5505:Static Routing and Deny TCP connection because of bad flag

Hi Everybody,
I have a problem. I made a VPN site-2-site with 2 ASA 5505. The VPN works great. And I create a redondant link if the VPN failed.
In fact, I use Dual ISP with route tracking. If the VPN fails, the default route change to an ISDN router, situated on the inside interface.
When I simulated a VPN fail, the ASAs routes switch automatically on backup ISDN routers. If I ping elements, it works great. But when i try TCP connection like telnet, the ASAs deny connections:
%PIX|ASA-6-106015: Deny TCP (no connection) from 172.16.10.57/35066 to 172.16.18.1/23 flags tcp_flags on interface interface_name.
the security appliance discarded a TCP packet that has no associated connection in the security appliance connection table. The security appliance looks for a SYN flag in the packet, which indicates a request to establish a new connection. If the SYN flag is not set, and there is not an existing connection, the security appliance discards the packet.
thanks!
EDIT: On the schema, The interface of the main asa is 172.16.18.148...

Check if the xlate timer is set greater than or equal to what the conn timer, so as not to have connections waiting on xlates that no longer exist. To minimize the number of attempts, enable "service resetinbound" . The PIX will reset the connection and make it go away. Without service resetinbound, the PIX Firewall drops packets that are denied and generates a syslog message stating that the SYN was a denied connection.

Anyone else having an issue with TCP connections using iCloud for Windows?

Hi,
Before I asked this question, I did wait to see if any related questions came up, but none did, so I submit it now.
On my admittedly older laptop running Windows 7 64b Home, I've run into difficulties with the iCloud for Windows app to the extent that I had to uninstall it.
It would that, as my laptop was running, in the background, iCloudServices.exe would endlessly iterate TCP connections, which, while not actively sending or receiving any data, after some hours would number over 100 instances, taking up resources, and grinding my laptop's WiFi connection to a grindingly slow pace. I ended up, within the app, turning off everything, iCloud Drive and Photos, (I never used bookmarks), but still this would continue to occur.
I contacted Apple Support, explaining what was going on, and they stated they only dealt with IOS and gave me a Microsoft Support number. When I called Microsoft support, I came more and more to the realization that the issue was specifically with the iCloud for Windows app, as that was the only software that was endlessly creating and not closing TCP connections as it was. How was Microsoft supposed to solve an issue with Apple code?
So I called Apple back, whereupon they insisted it was a Microsoft issue. I explained other cloud services installed on the same computer were not having the same issue, it was unique to ICloudServices.exe. They stated they only dealt with IOS. I stated I purchased an iPad Air less than 7 months ago, and was trying to run iCloud in support of that. They again stated they only dealt with IOS, and suggested I again try Microsoft. I asked them if it was reasonable to expect Microsoft to solve issues with Apple code? They said regardless, there was zero support offered for anything having to do with Windows, and all I could do was uninstall the app, which I did, though that did not feel very satisfactory to me. My thinking is, if Apple writes a Windows app in support of their hardware, they should offer support for it.
Anyway, I was just wondering, is this an issue unique to me? or have others experienced a similar issue? I found this issue by opening the Windows Resource Monitor, looking under the Networking tab, and scrolling through the TCP Connections section to find 100+ concurrent iCloudServices.exe instances listed, whereas even Chrome, with multiple tabs and extensions, topped out at around 20.
My one month old Desktop, DYI, sports a solid Asus 1150 MoBo, i7-4790k cpu, 16GB Ram, and an EVGA GTX 970 video card. I list some specs only to illustrate this computer has no hardware issues in comparison to my long in tooth laptop. On this desktop, running Win 8.1 Pro 64b, at least as many, identifiably Apple, background service TCP connections are created even compared to Chrome, regardless of many tabs being open, many extensions, and even some related apps. Adobe does not even come close, though I run the full CC subscription. On this new computer, running Windows 8.1 Pro 64b, there are currently over 50 TCP connections and loopbacks that do not identify themselves, with just a - for the Image, and PID. With the experience on my laptop, I wonder how many of these are generated by Apple software, if not specifically iCloud software?
The frustrating aspect of these connections is they seem in no way active, While the Chrome and Adobe connections can be seen to be transferring data, as long as I am not running iTunes, or so have my iPad actually plugged in, it seems 99% of the time these iCloudServices.exe connections are just taking up ports, neither sending nor receiving any data discernable to me under the Processes with Network Activity, or Network Activity lists, both displayed in the same window as the TCP Connections in the Windows Resource Monitor.
Though I am fairly ignorant as regards coding, it seems as if there is no call to close a connection, very specifically, iCloudServices.exe, when it is no longer needed, and the next time a connection is needed, a new one is opened, rather than accessing the one previously opened. The only other reason I could imagine this might be occurring is if my Norton Internet Security software might mask and/or block the port after a certain time of inactivity.
Anyone out there have any ideas or advice about this? Thanks in advance.

Thanks jared,
I'm still dealing with this issue through Apple. Some time after I posted this, I contacted Apple again. They did start a case up for me, as I was experiencing the same behavior on two different machines, with two different versions of Windows.
So far it remains unsolved. I've logged iClouds for Windows on my desktop, which is brand new, then logged for awhile after completely uninstalling Norton Security Suite, depending on the Microsoft security for some time, and finally logged after I uninstalled iCloud for Windows, restarted, installed a clean download, and connected using a completely different test account, which Apple set up for me. None of this made any difference. Looking at the logs, it seems every 10 minutes, iCloudServices.exe creates a new TCP connection to confirm I'm using less than 5GB on iCloud, (which I am by a good margin, using less than 2GB), it seems this connection is not closed, and when the next iteration rolls around 10 minutes later, a new TCP connection is created. I come very close to having 6 TCP connections created per hour, until I restart my computer. This works out to... 6 x 24 = 144/day.
Perhaps the article you posted will shed some further light on this. I'm thinking seeing the state of the connection through netstats, at the least, could help.
For the last week, I've been putting a hold on further logging, as Apple wants me to create a new user account on one of my computers, install iCloud for Windows there, and log it running in the other account. This however basically means I cannot use my computer for a fair number of hours, and I've been busy enough with work the past week that I haven't the time or energy to afford to set this up and run it. I've had need of my computers too much for the past week.

TCP connection in labview and C program

Hi there,
I have a server program written in C and running under linux, it
accept connection from client and send series of data to client
through TCP socket. I was using the "simple data client.vi" as the
client.
I tried to send integer number 1, 2,3.. , but the client failed to
correctly decode the data since it read everything as string. I was
wondering if there is a solution to read binary data in labview TCP
connection? I really don't want to encode the double into string and
send it to client through TCP socket in my server program, since it's
not efficient.
thanks !

> I have a server program written in C and running under linux, it
> accept connection from client and send series of data to client
> through TCP socket. I was using the "simple data client.vi" as the
> client.
> I tried to send integer number 1, 2,3.. , but the client failed to
> correctly decode the data since it read everything as string. I was
> wondering if there is a solution to read binary data in labview TCP
> connection? I really don't want to encode the double into string and
> send it to client through TCP socket in my server program, since it's
> not efficient.
> thanks !
>
The string is often used in LV as a general buffer. Type Cast the
string as the appropriate integer and it should be fine. If the integer
has been transmitted in litt
le endian byte order, you will need to use
the Advanced byte and word swapping functions in LV in order to reorder
the integer contents -- LV always assumes big-endian binary format.
Greg McKaskle

Monitoring total number of JDBC connections

We have our application deployed in the Oracle 10g Application server, it uses Toplink 10g for the Persistence and OR mapping and the Oracle 9i database for data storage, the database connection pool is built and maintained by Toplink.
We observed that on the administration screen for each container, there are 2 parameters, number of active database connections and the total number of JDBC connections.
We did some load testing for the application and observed the following behaviour on the container.
1. When the number of parallel users are 10, behaviour seems to be normal, the active database connections are less than 20(used by the connection pool built by Toplink) and the total number of JDBC connections is the same as the number of database connections.
2. When the number of parallel users is increased to 50, we see that the active database connections is still less than 20, but the total number of JDBC connections just blowed up to 4000+ in less than 2 minutes and still growing. We have no valid explanation for this behaviour as the active sessions is still less than 20. Also we see no obnormal behaviour in our application log files.
The questions i have are
1. What could be the reason for the above abnormal behaviour?
2. How this parameter "Total number of JDBC connections" for a container is actually measured?
3. DOes this parameter gets affected by how we run the database i.e. in Dedicated server mode or Despactcher mode?
Many thanks for any information on this topic..

Perhaps your connection inactivity timeout is slightly too low, so that your connections are being closed and reopened at almost the same frequency. Try increasing the timeout.
Good Luck,
Chris

SbRIO-9612 unable to close a TCP connection without causing TCP failure

Hello,
I'm working on a multi-server (sbRIO-9612's), multi-client (Windows PCs) application which uses the STM 2.0 libraries and LV2009 SP1. The server listens on a UDP port for the client to send a message - once sent, the server opens the TCP connection to the client and all is well . . .
. . . until I added a "hearbeat" message to monitor for down connections. Once the TCP connection has been extablished, the client PC sends a TCP message (a request for the number of clients connected) to the server sbRIO-9612 every 5 seconds - both the client and server are coded to close the connection if a message is not received within 10 seconds. The client-side app works fine - if the TCP message is not returned in 10 seconds, the connection is closed and a new UDP message is sent to re-establish it.
The server-side is the problem - if no message is received in 10 seconds, the TCP connection is closed o.k. (no errors), but the server will no longer allow new TCP connections to be established unless it's rebooted. It seems to work fine if I leave the non-communicating TCP connections open on the server-side, but I can see this leading to problems after several clients have disconnected without notifying the server properly.
Interestingly, if the client closes the TCP connection properly (via TCP Close in LV), the server detects it fine and there is no problem.
I'm allowing the operating system on both sides to select the TCP port to use.
Any help is greatly appriciated - thank you!
Al

Hi Al,
Thanks for the update -- I'm glad that you were able to find that the issue wasn't actually with the TCP VIs, and moreover that LabVIEW 2010 SP1 seems to have resolved the issue. I would still recommend combing through the code on the RT end to ensure that the LabVIEW 2010 SP1 upgrade really did 'fix' the underlying issue. It's somewhat strange that a version upgrade resolved TCP communication issues that you were having. I just want to be sure that the solution is a truly stable one.
Sanjay C.
Embedded Software Product Manager| National Instruments

Huge number of idle connections from loopback ip on oracle RAC node

Hi,
We have a 2node 11gR2(11.2.0.3) oracle RAC node. We are seeing huge number of idle connection(more than 5000 in each node) on both the nodes and increasing day by day. All the idle connections are from VIP and loopback address(127.0.0.1.47971 )
netstat -an |grep -i idle|more
127.0.0.1.47971 Idle
any insight will be helpful.
The server is suffering memory issues occasionally (once in a month).
ORA-27300: OS system dependent operation:fork failed with status: 11
ORA-27301: OS failure message: Resource temporarily unavailable
Thanks

user12959884 wrote:
Hi,
We have a 2node 11gR2(11.2.0.3) oracle RAC node. We are seeing huge number of idle connection(more than 5000 in each node) on both the nodes and increasing day by day. All the idle connections are from VIP and loopback address(127.0.0.1.47971 )
netstat -an |grep -i idle|more
127.0.0.1.47971 Idle
any insight will be helpful.
The server is suffering memory issues occasionally (once in a month).
ORA-27300: OS system dependent operation:fork failed with status: 11
ORA-27301: OS failure message: Resource temporarily unavailable
Thankswe can not control what occurs on your DB Server.
How do I ask a question on the forums?
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SELECT * FROM V$VERSION;

Increase number of TCP connections

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