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POWriting into file under NFS in Grails app using Quartz and RabbitMQ
 

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  1. POWriting into file under NFS in Grails app using Quartz and RabbitMQ
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    <p>We have a Grails app, that uses RabbitMQ for passing messages. The architecture we have for the production environent is:<br> - 2 web servers, let's say web1, web2. Both of them run an instance of a grails app<br> - a RabbitMQ server is installed on only one of the servers, web1<br> - In the RabbitMQ configuration in the Grails app, we have 10 consumers (per application instance) </p> <p>We have a Quartz job that creates some messages and passes them to the queue, and we have a consumer service that handles the messages getting in the queue.<br> 1. How can we define which server (application instance)should execute the Quartz job? I assume there's only one server running the Job and Quartz is taking care of that.<br> 2. How can we define which server handles the messages from the queue? </p> <p>The problem is, that the methods that consume the queue messages, eventually write some rows in a .csv file, which is under NFS. </p> <p>Initially we had some <a href="https://stackoverflow.com/questions/5104074/writing-to-file-with-groovygrails-fails-for-some-lines-broken-lines">issues</a>, with the actual writing in the .csv file. There were some "broken", half-written rows in the file, but we resolved this by adding @Synchronized on the method that wrote in the .csv file. Now the issue is, that some rows, just don't get written at all. </p> <p>Any ideas? I am not sure whether this is a programming issue, and if so how could it be resolved, or if it is an architectural issue. </p> <p><strong>UPD</strong>:@Olexandr<br> Initially I had (example) <code><pre>def getStringsToWrite(File file, List someOtherList) { def stringsList = [] someOtherList.each { def someString = "someString" stringsList &lt;&lt; someString } writeRowsToFile(file, stringsList) }</p> <p>@Synchronized def writeRowsToFile(File file, List stringsList) { file.withWriterAppend {out-> stringsList.each {row-> out.writeLine row } } } </pre></code></p> <p>And it did was not working "properly"</p> <p>Now, I changed the code to something like: <pre> class someServiceClass { //singleton <strong>LinkedBlockingQueue csvWritingQueue = new LinkedBlockingQueue()</strong> </p> <p>def getStringsToWrite(File file, List someOtherList) { def stringsList = [] someOtherList.each { def someString = "someString" <strong>csvWritingQueue.put(someString)</strong> } writeRowsToFile(<strong>file</strong>) }</p> <p>@Synchronized def writeRowsToFile(File file) { file.withWriterAppend {out-> <strong>while (!csvWritingQueue.isEmpty()) {</strong> <strong>out.writeLine csvWritingQueue.poll()</strong> } } } } </pre> </p> <p>Please let me know if you need any additional info. I tried to keep it at a high level perspective, but I will be more than happy to include some code in the post. </p> <p>Thanks in advance,<br> Iraklis</p>
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