Обсуждение: Connection with server dropping out
Hi all, I'm hoping someone could help me with this issue, not sure if the general mailing list is the right place so apologies if this needs to be directed else where. We have several clients who are experiencing disconnects to our hosted postgres server. From the server side we simply see a "could not receive data from client: Connection reset by peer" error. On the client side we generally see a "could not receive data from server: The system cannot find the path specified.". Googling around the indication seems to be that a firewall or router in between the client and the server may be dropping the connection considering it inactive. We have setup keep alives (currently every 5 seconds as a test) and that has improved the situation but as our client application is a single threaded application and it is possible for it to be processing data and thus not respond the connection may still be deemed inactive. My first question is, if it is the keep alive itself (currently set to 10 retries every 5 seconds) decides that the connection is dead, would we see a different message in the logs? My second question is, does anyone know what the most likely culprit is and been able to change the configuration there? This is on a Postgres 8.4 server running on CentOS but we've also experienced this in relation to a Postgres 9.1 server Kindest Regards, Bastiaan Olij
On 02/18/2013 10:37 PM, Bastiaan Olij wrote: > Hi all, > > I'm hoping someone could help me with this issue, not sure if the > general mailing list is the right place so apologies if this needs to be > directed else where. > > We have several clients who are experiencing disconnects to our hosted > postgres server. From the server side we simply see a "could not receive > data from client: Connection reset by peer" error. > > On the client side we generally see a "could not receive data from > server: The system cannot find the path specified.". > > Googling around the indication seems to be that a firewall or router in > between the client and the server may be dropping the connection > considering it inactive. We have setup keep alives (currently every 5 > seconds as a test) and that has improved the situation but as our client > application is a single threaded application and it is possible for it > to be processing data and thus not respond the connection may still be > deemed inactive. > > My first question is, if it is the keep alive itself (currently set to > 10 retries every 5 seconds) decides that the connection is dead, would > we see a different message in the logs? > > My second question is, does anyone know what the most likely culprit is > and been able to change the configuration there? > > This is on a Postgres 8.4 server running on CentOS but we've also > experienced this in relation to a Postgres 9.1 server The part that has me a little confused is: "... The system cannot find the path specified." This looks more like a path issue than a connection issue. What is the client program ? What OS(es) is it running on? Is it just fetching data from the server or is it also running a remote program? > > Kindest Regards, > > Bastiaan Olij > > -- Adrian Klaver adrian.klaver@gmail.com
Hey Adrian > > The part that has me a little confused is: > > "... The system cannot find the path specified." > > This looks more like a path issue than a connection issue. > > What is the client program ? > > What OS(es) is it running on? > > Is it just fetching data from the server or is it also running a > remote program? I have no idea where the message originates from. The client environment is Omnis Studio (http://www.tigerlogic.com/tigerlogic/omnis/). We experience this issue on Mac OS X and possibly Windows as well (we have several clients on Windows). The issue happens add random moments within the application often after it has sat idle for a little while or after its ran a lengthy client side process. Cheers, Bastiaan Olij
On 02/19/2013 12:28 PM, Bastiaan Olij wrote: > Hey Adrian >> >> The part that has me a little confused is: >> >> "... The system cannot find the path specified." >> >> This looks more like a path issue than a connection issue. >> >> What is the client program ? >> >> What OS(es) is it running on? >> >> Is it just fetching data from the server or is it also running a >> remote program? > I have no idea where the message originates from. The client environment > is Omnis Studio (http://www.tigerlogic.com/tigerlogic/omnis/). We > experience this issue on Mac OS X and possibly Windows as well (we have > several clients on Windows). So where did you find this message listed in your original post: "On the client side we generally see a "could not receive data from server: The system cannot find the path specified."." > > The issue happens add random moments within the application often after > it has sat idle for a little while or after its ran a lengthy client > side process. > > Cheers, > > Bastiaan Olij > > > -- Adrian Klaver adrian.klaver@gmail.com
Hey Adrian, > > So where did you find this message listed in your original post: > > "On the client side we generally see a "could not receive data from > server: The system cannot find the path specified."." Owh sorry, I'll explain a bit deeper. Omnis Studio is a development environment that we use to develop our software with. Obviously there is some middleware involved that allows software written in Omnis to talk to a postgres backend and that bit is a bit of a black box obviously. As far as I'm aware it's a very thin layer directly talking to the postgres client libraries. It is hard for me to tell whether the error is returned by the postgres client libraries and passed back to my code as is or whether this is an internal error returned by the code written by TigerLogic. Googling on it I did however find some references to this error coming up in pgAdmin making me suspect the former. I can't pin the error to any query we're executing against postgres, it seems to happen at random intervals with whatever code is running at that given time which is making it very frustrating to debug which is why I'm suspecting some outside influence. As we've got many users connecting to our server who do not experience this I'm also inclined to think the source of the issue is neither in the client nor the server but something that happens in between. I'm just hoping someone else ran into this situation and was able to find a cause and offer a solution. Cheers, Bastiaan Olij
On 02/19/2013 03:46 PM, Bastiaan Olij wrote: > Hey Adrian, >> >> So where did you find this message listed in your original post: >> >> "On the client side we generally see a "could not receive data from >> server: The system cannot find the path specified."." > > Owh sorry, I'll explain a bit deeper. Omnis Studio is a development > environment that we use to develop our software with. Obviously there is > some middleware involved that allows software written in Omnis to talk > to a postgres backend and that bit is a bit of a black box obviously. As > far as I'm aware it's a very thin layer directly talking to the postgres > client libraries. > > It is hard for me to tell whether the error is returned by the postgres > client libraries and passed back to my code as is or whether this is an > internal error returned by the code written by TigerLogic. Googling on > it I did however find some references to this error coming up in pgAdmin > making me suspect the former. > > I can't pin the error to any query we're executing against postgres, it > seems to happen at random intervals with whatever code is running at > that given time which is making it very frustrating to debug which is > why I'm suspecting some outside influence. As we've got many users > connecting to our server who do not experience this I'm also inclined to > think the source of the issue is neither in the client nor the server > but something that happens in between. > > I'm just hoping someone else ran into this situation and was able to > find a cause and offer a solution. So what OS is your Postgres server running on? From what I gather "The system cannot find the path specified" is Microsoft specific, so I am not quite sure how it is showing up on the Mac clients? > > Cheers, > > Bastiaan Olij > > > > > -- Adrian Klaver adrian.klaver@gmail.com