> Not sure about Tomcat, but what IBM Liberty does is: > > It "will" try to redeploy the war when it detects a file change - and it > does fail naturally since the war isn't complete. > > BUT - it will keep trying since during the upload, the timestamp and file > size automatically keeps changing - so at the end, it will succeed in > deploying the whole war file.
I may be wrong but I thought .war files are zip files. Wouldn't it be possible to just wait until the file has a consistent content and then extract it? Simon > > I wish they would have just monitored the file size for a configurable > "given" time. And lets say - if the file size or timestamp doesn't change > for -say - 15 seconds, then go ahead and do the deployment, but as what > was mentioned earlier, different OS(s) may handle this differently, but > the JAVA NIO API watchevents point you in the right direction in watching > a file/folder in a loop for a "create" or "modify" or "delete" event to > occur and fire off. > > thanks, > jason > > ----- Original Message ----- > From: "chris" <ch...@christopherschultz.net> > To: "users" <users@tomcat.apache.org> > Sent: Sunday, February 20, 2022 9:22:17 AM > Subject: Re: <Context … reloadable = "true"> is too quick to respond > > John, > > On 2/20/22 05:50, John Barrow wrote: >> Neil, >> >> Thanks for your useful feedback. I am still feeling my way as you can >> probably see from my earlier emails trying to setup a development >> environment. >> >> I did actually think of this but didn't put it in scope for a couple of >> reasons. >> >> Firstly, the Tomcat documentation for readloadable quotes >> >> "Set to true if you want Catalina to monitor classes in >> /WEB-INF/classes/ and /WEB-INF/lib for changes, and automatically >> reload the web application if a change is detected. This feature is >> very useful during application development, but it requires >> significant runtime overhead and is not recommended for use on >> deployed production applications. That's why the default setting for >> this attribute is false. You can use the Manager web application, >> however, to trigger reloads of deployed applications on demand." >> >> Therefore, I took it to mean that this flag was geared at development, >> not production which is what I assume when you would deploy a .war >> file. So Tomcat would be listening to specific changes in .classes and >> .jar files that had just been compiled and these are normally small in >> size. But then I suppose that a single .jar file may be so sized that >> Tomcat could react while the file was still being written to the disk. > > The patch you are currently working on should fix this aspect of the > overall problem you are trying to solve. > >> Secondly, I sort of assumed that since the feature was already in >> place and handles changes to single files that this check for >> completeness has already been implemented, but then as I can't get a >> development environment to run, I don't have enough skills to drill >> into the sources without it being interactive to help me explore and >> learn. >> >> However, it makes sense that your recommendation is implemented, >> although I was imagining setting the delay to (say) 500ms to ensure >> that whatever IDE had time to complete the copying of all the files as >> that is a small price to pay for automatic refresh. Also by resetting >> the timer after each event it would have to be quite a large upload >> for Tomcat to start reacting. >> >> Like you, I am not sure how to formally check that a file has >> completed its copy to the destination. The most common suggestion I >> hear is to try and change its name and then change it back again and >> capture the exception which will be raised if the file is locked. I >> wonder whether attempting to set an attribute (e.g.toggle read-only) >> would have the same effect (i.e. only allow if file wasn't locked) and >> be a little more elegant. I would have to try it. > > Don't do anything like that; it won't work on various environments. For > example, Windows obtains exclusive file-locks for even sometimes > read-only operations. But *NIX does /not/. So you may develop something > that works on Windows but doesn't work at all anywhere else. > > You basically can't check to see if a file is "done uploading"" or > whatever else may be happening. What you *can* do is check to see if any > file in the list-of-files-to-be it *too recent* indicating that a > compile/copy/upload/whatever may still be in progress. > >> I assume that Windows has a way of querying a file lock but not sure >> (a) whether that is exposed via a Java API and (b) whether that would >> apply to Unix as well (as I have only ever used Windows for >> development). >> >>> How does Tomcat test if a file has been updated? > > It's just relative timestamps. Dive into the code Mark suggested and > you'll find it. > >> Again, I don't know this yet (lack of IDE again), but I assumed that >> it would be similar to the method I implemented in the attached source >> code, i.e. Create a listener for events being triggered on file >> changes to either /WEB-INF/classes/ and /WEB-INF/lib, as they are both >> hard-coded file paths. > > I don't think your attachment made it to the list. Maybe you can host it > somewhere else and then post a URL to the list? Attachments tend to be > stripped. I'm actually surprised your ZIP file made it through. > >> As an aside, I should have mentioned, for anyone interested in this >> thread and in case not obvious from the source, but to see the sample >> source code in action, you need to add, modify, rename or delete files >> within the specified directory in a File Explorer. > > -chris > >> On Sun, 20 Feb 2022 at 00:04, Neil Aggarwal <n...@propfinancing.com> >> wrote: >>> >>> John: >>> >>>> If anyone has a moment, can you have a quick look and see if what I am >>>> proposing seems acceptable. >>> >>> Thinking about when a large file (Such as a war file) is being uploaded >>> to the server, we don't want Tomcat to reload it until after the file >>> has >>> completed upload and is fully formed. >>> >>> How does Tomcat test if a file has been updated? >>> I assume it uses File.lastModified() or something similar. >>> >>> Does anyone know the detailed nuts and bolts of how that works? >>> Does last modified keep changing as the file is uploading or is it just >>> changed at the start of the upload? Is the behavior the same or >>> different >>> across platforms? >>> >>> These questions should be taken into account when designing the >>> solution. >>> >>> Thank you, >>> Neil >>> >>> -- >>> Neil Aggarwal, (972) 834-1565, http://www.propfinancing.com >>> We offer 30 year loans on single family houses! >>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >>> For additional commands, e-mail: users-h...@tomcat.apache.org >>> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> For additional commands, e-mail: users-h...@tomcat.apache.org >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
