| Re: [jetty-users] ServletContextListener defers server start |
(and return after the 503)
On 10/7/19 7:35 AM, Bill Ross wrote:
> Would anything like these chunks from my code work for you? The secret
> is checking status in doGet().
>
>
> public class GetMult extends HttpServlet {
>
> private ServletData servletData;
>
> public void init(ServletConfig config) throws ServletException {
>
> servletData = ServletData.get(); // singleton
>
> }
>
> @Override
> public void doGet(HttpServletRequest req, HttpServletResponse res)
> throws ServletException, IOException {
>
> if (!servletData.isReady()) {
>
> res.sendError(503, "Put another quarter million in the
> slot");
>
> }
>
> // do it
>
> }
>
> }
>
> public class ServletData {
>
> private static Logger log =
> LoggerFactory.getLogger(ServletData.class);
>
> // calling the constructor here hangs sync on the parallel loads
> // for some reason
> private static ServletData single = null;
>
> public static ServletData get() {
> synchronized(ServletData.class) {
> if (single == null) {
> single = new ServletData();
> }
> }
> return single;
> }
>
> private ServletData() {
>
> Thread th1 = new Thread(new Runnable() {
> public void run() {
> try {
> approvedV =
> ApprovalDao.getAllApprovedPairs(fconn, 1,
> "v", null,
> true, // d0
> null, null,
> null);
> } catch (SQLException sqe) {
> log.error("approvedV: " + sqe);
> System.exit(1);
> }
> }
> });
> th1.start();
>
> }
>
> public isReady() {
>
> return approvedV != null;
>
> }
>
> }
>
> On 10/7/19 5:34 AM, Dirk Olmes wrote:
>> On 10/7/19 11:21 AM, Bill Ross wrote:
>>> Why not have a ContextHandler that starts a setup thread on init, and
>>> answers 503 until that thread is done?
>> That's sort of what I currently do (starting a setup thread from the
>> main servlet's init method) but that causes all kinds of trouble because
>> the servlet context accepts requests before all the app logic is ready.
>>
>> Based on your suggestion combined with Greg's before I came up with this
>> approach: Register a ContextHandler that answers 503 and let the server
>> start normally. After the server is started I launch the setup thread
>> where I register the real app context with the server and manually send
>> it a start(). After the context is started I unregister the
>> ContextHandler that answers 503.
>>
>> The code is here:
>> https://github.com/dirk-olmes/jetty-delayed-context-startup/tree/deferred_context_startup
>>
>>
>> Ok, this approach works. But I was hoping that Jetty supported something
>> like that out of the box.
>>
>> -dirk
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