Re: WebCatalog Eating 200% of the CPU
This WebDNA talk-list message is from 2002
It keeps the original formatting.
numero = 44949
interpreted = N
texte = Are you talking about exclusivelock or are there other 'tricks' as well?On 11/5/02 11:11 AM, Scott Anderson mashed the following keys :> What do you mean by 'clean'? A template may contain valid WebDNA syntax, > but could still take a long time to process. I would consider such a > template 'not' a very good candidate for a generally accessible WebDNA > template. > > Your argument assumes that you (or a hacker) have knowledge of a particular > template (or were able to create a template) on the server that can tie up > the engine enough to overwhelm it by sending several http requests for that > template. If no such template existed, then there is not a risk. Again, > this boils down to how carefully and efficiently you have programmed your > templates. > > If it is necessary to create a WebDNA template that will take a large amount > of time to complete (often some admin process), then you should put the > necessary WebDNA code in place to synchronize access to that template to > ensure that only one instance of that template will run at any given time. > Templates that you serve to the general public should be 'lean and mean' and > not 'over loaded' with to much code. > >> why have the preference? > A high performance server can handle a larger number of http requests, so > that preference allows a WebDNA admin to adjust the thread limit > accordingly. > >> -----Original Message----- >> From: WebCatalog Talk >> [mailto:WebDNA-Talk@talk.smithmicro.com]On Behalf >> Of Alain Russell >> Sent: Monday, November 04, 2002 7:38 PM >> To: WebCatalog Talk >> Subject: Re: WebCatalog Eating 200% of the CPU >> >> >> Scott, >> >> I disagree here a bit - If I can bring down another persons >> server that is >> running code that is 'clean' then surely that sets us all up for DOS >> attacks? >> >> If the engine running in multithreaded mode starts so many >> threads that it >> goes into a zombie state and does not respond to any requests >> why have the >> preference? >> >> Were not talking about bringing the engine to a crawl - when >> I simulate this >> the engine stops responding totally. The machine it is running on gets >> unresponsive and a lot of the time the only way to fix it is >> hard reset. >> >> Alain >> >> >> >>> This is not necessarily a bug with the engine. If you >> intentionally (or >>> accidentally) create a template that performs 10s of >> thousands of searches, >>> or that contains a huge number of iterations on a block of >> WebDNA code, to >>> the point where it takes several minutes for the template >> to complete; then >>> if that template is requested dozens of times within a few >> seconds, it would >>> be easy to bring the engine to a crawl. This is why it is >> important for the >>> WebDNA programmer (or any programmer) to exercise some >> caution with their >>> code. It is always a good idea lookout for possible >> infinite or very large >>> loops, redundant code, assumptions in form data, etc... >>> >>> It would be easy to write a C++ application that >> intentionally brings an OS >>> to its knees, so would that be the fault of the OS? >>> >>> However, there are a couple of preferences that may help to >> prevent a WebDNA >>> overload. The 'Max Search Results' was intended to prevent >> an accidental >>> iteration of a large number of search results in the >> [founditems] loop. We >>> have also added a new pref that allows you to control the >> maximum number of >>> concurrent threads the WebDNA engine can spawn. Both of >> those may help. >>> But again, there is no substitute for thorough testing of >> WebDNA template >>> code before going to production. >>> >>> >>> >>>> -----Original Message----- >>>> From: WebCatalog Talk >>>> [mailto:WebDNA-Talk@talk.smithmicro.com]On Behalf >>>> Of Alain Russell >>>> Sent: Monday, November 04, 2002 6:00 PM >>>> To: WebCatalog Talk >>>> Subject: Re: WebCatalog Eating 200% of the CPU >>>> >>>> >>>> No I think it is supposed to catch the 'Zombie' state - >>>> perhaps a little >>>> more work is needed ?? Perhaps this is why the 4.5 patch >>>> seems to have been >>>> delayed ;) >>>> >>>>> On 11/4/02 4:37 PM, Alain Russell >>>>
wrote: >>>>> >>>>>> Aaron & I had a discussion about this the other day. >>>>>> I've reported to SMSI a while ago about WebDNA doing this >>>> with 'good' >>>>>> searches when the pages are loaded .. >>>>>> >>>>>> Say you have a slow/big search that is coded right - hit >>>> is a few times >>>>>> quickly and this condition can happen. >>>>>> >>>>>> Check the archives for the discussion. >>>>> >>>>> Any response from Smith Micro? I thought WebCatalog >>>> Monitor was supposed to >>>>> catch these situations, or is that only when WebCatalog quits? >>>>> >>>>> Thanks >>>> >>>> >>>> ------------------------------------------------------------- >>>> This message is sent to you because you are subscribed to >>>> the mailing list . >>>> To unsubscribe, E-mail to: >>>> To switch to the DIGEST mode, E-mail to >>>> >>>> Web Archive of this list is at: http://search.smithmicro.com/ >>> >>> ------------------------------------------------------------- >>> This message is sent to you because you are subscribed to >>> the mailing list . >>> To unsubscribe, E-mail to: >>> To switch to the DIGEST mode, E-mail to >>> >>> Web Archive of this list is at: http://search.smithmicro.com/ >> >> >> ------------------------------------------------------------- >> This message is sent to you because you are subscribed to >> the mailing list . >> To unsubscribe, E-mail to: >> To switch to the DIGEST mode, E-mail to >> >> Web Archive of this list is at: http://search.smithmicro.com/ > > ------------------------------------------------------------- > This message is sent to you because you are subscribed to > the mailing list . > To unsubscribe, E-mail to: > To switch to the DIGEST mode, E-mail to > > Web Archive of this list is at: http://search.smithmicro.com/ > ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list . To unsubscribe, E-mail to: To switch to the DIGEST mode, E-mail to Web Archive of this list is at: http://search.smithmicro.com/
Associated Messages, from the most recent to the oldest:
Are you talking about exclusivelock or are there other 'tricks' as well?On 11/5/02 11:11 AM, Scott Anderson mashed the following keys :> What do you mean by 'clean'? A template may contain valid WebDNA syntax, > but could still take a long time to process. I would consider such a > template 'not' a very good candidate for a generally accessible WebDNA > template. > > Your argument assumes that you (or a hacker) have knowledge of a particular > template (or were able to create a template) on the server that can tie up > the engine enough to overwhelm it by sending several http requests for that > template. If no such template existed, then there is not a risk. Again, > this boils down to how carefully and efficiently you have programmed your > templates. > > If it is necessary to create a WebDNA template that will take a large amount > of time to complete (often some admin process), then you should put the > necessary WebDNA code in place to synchronize access to that template to > ensure that only one instance of that template will run at any given time. > Templates that you serve to the general public should be 'lean and mean' and > not 'over loaded' with to much code. > >> why have the preference? > A high performance server can handle a larger number of http requests, so > that preference allows a WebDNA admin to adjust the thread limit > accordingly. > >> -----Original Message----- >> From: WebCatalog Talk >> [mailto:WebDNA-Talk@talk.smithmicro.com]On Behalf >> Of Alain Russell >> Sent: Monday, November 04, 2002 7:38 PM >> To: WebCatalog Talk >> Subject: Re: WebCatalog Eating 200% of the CPU >> >> >> Scott, >> >> I disagree here a bit - If I can bring down another persons >> server that is >> running code that is 'clean' then surely that sets us all up for DOS >> attacks? >> >> If the engine running in multithreaded mode starts so many >> threads that it >> goes into a zombie state and does not respond to any requests >> why have the >> preference? >> >> Were not talking about bringing the engine to a crawl - when >> I simulate this >> the engine stops responding totally. The machine it is running on gets >> unresponsive and a lot of the time the only way to fix it is >> hard reset. >> >> Alain >> >> >> >>> This is not necessarily a bug with the engine. If you >> intentionally (or >>> accidentally) create a template that performs 10s of >> thousands of searches, >>> or that contains a huge number of iterations on a block of >> WebDNA code, to >>> the point where it takes several minutes for the template >> to complete; then >>> if that template is requested dozens of times within a few >> seconds, it would >>> be easy to bring the engine to a crawl. This is why it is >> important for the >>> WebDNA programmer (or any programmer) to exercise some >> caution with their >>> code. It is always a good idea lookout for possible >> infinite or very large >>> loops, redundant code, assumptions in form data, etc... >>> >>> It would be easy to write a C++ application that >> intentionally brings an OS >>> to its knees, so would that be the fault of the OS? >>> >>> However, there are a couple of preferences that may help to >> prevent a WebDNA >>> overload. The 'Max Search Results' was intended to prevent >> an accidental >>> iteration of a large number of search results in the >> [founditems] loop. We >>> have also added a new pref that allows you to control the >> maximum number of >>> concurrent threads the WebDNA engine can spawn. Both of >> those may help. >>> But again, there is no substitute for thorough testing of >> WebDNA template >>> code before going to production. >>> >>> >>> >>>> -----Original Message----- >>>> From: WebCatalog Talk >>>> [mailto:WebDNA-Talk@talk.smithmicro.com]On Behalf >>>> Of Alain Russell >>>> Sent: Monday, November 04, 2002 6:00 PM >>>> To: WebCatalog Talk >>>> Subject: Re: WebCatalog Eating 200% of the CPU >>>> >>>> >>>> No I think it is supposed to catch the 'Zombie' state - >>>> perhaps a little >>>> more work is needed ?? Perhaps this is why the 4.5 patch >>>> seems to have been >>>> delayed ;) >>>> >>>>> On 11/4/02 4:37 PM, Alain Russell >>>> wrote: >>>>> >>>>>> Aaron & I had a discussion about this the other day. >>>>>> I've reported to SMSI a while ago about WebDNA doing this >>>> with 'good' >>>>>> searches when the pages are loaded .. >>>>>> >>>>>> Say you have a slow/big search that is coded right - hit >>>> is a few times >>>>>> quickly and this condition can happen. >>>>>> >>>>>> Check the archives for the discussion. >>>>> >>>>> Any response from Smith Micro? I thought WebCatalog >>>> Monitor was supposed to >>>>> catch these situations, or is that only when WebCatalog quits? >>>>> >>>>> Thanks >>>> >>>> >>>> ------------------------------------------------------------- >>>> This message is sent to you because you are subscribed to >>>> the mailing list . >>>> To unsubscribe, E-mail to: >>>> To switch to the DIGEST mode, E-mail to >>>> >>>> Web Archive of this list is at: http://search.smithmicro.com/ >>> >>> ------------------------------------------------------------- >>> This message is sent to you because you are subscribed to >>> the mailing list . >>> To unsubscribe, E-mail to: >>> To switch to the DIGEST mode, E-mail to >>> >>> Web Archive of this list is at: http://search.smithmicro.com/ >> >> >> ------------------------------------------------------------- >> This message is sent to you because you are subscribed to >> the mailing list . >> To unsubscribe, E-mail to: >> To switch to the DIGEST mode, E-mail to >> >> Web Archive of this list is at: http://search.smithmicro.com/ > > ------------------------------------------------------------- > This message is sent to you because you are subscribed to > the mailing list . > To unsubscribe, E-mail to: > To switch to the DIGEST mode, E-mail to > > Web Archive of this list is at: http://search.smithmicro.com/ > ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list . To unsubscribe, E-mail to: To switch to the DIGEST mode, E-mail to Web Archive of this list is at: http://search.smithmicro.com/
Aaron Lynch
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