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POIs there any flaw in this code?
 

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  1. POIs there any flaw in this code?
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    <p>I wrote a servlet, but the servlet is not yet in production stage.</p> <p>I've added a counter in the Filter of the servlet, so that when number of concurrent request reach a limit, no more people can be accepted. I worry some marginal case, for example: Say the system has already reached 49 concurrent request(50 is max), and in the synchronized block it makes the boolean variable "ok" to True, then at the next instance, multiple thread see that the servlet is available and rush into that and break the limit.</p> <p>Please help to check this code if there is any flaw:</p> <pre><code>public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { // TODO Auto-generated method stub // place your code here // pass the request along the filter chain conditionalInfoLog(logEnabled, "Incoming request..."); conditionalInfoLog(logEnabled, "Number of concurrent request(s): " + count); boolean ok; synchronized (lock) { ok = count &lt; limit; if(ok){ count++; } } if (ok) { try{ // let the request through and process as usual conditionalInfoLog(logEnabled, "Request accepted and processing, number of concurrent request(s): " + count); chain.doFilter(request, response); }catch(Exception ex){ conditionalErrorLog(logEnabled, ex.getMessage()); String xmlStr = genXmlErrMsg(ex.getMessage()); response.setContentType("text/xml"); response.getWriter().print(xmlStr); }finally{ synchronized (lock) { count--; } conditionalInfoLog(logEnabled, "End of request. Number of concurrent request(s): " + count); } } else { // handle limit case, e.g. return status code 503 conditionalInfoLog(logEnabled, busyMsg); String xmlStr = genXmlErrMsg(busyMsg); response.setContentType("text/xml"); response.getWriter().print(xmlStr); } } </code></pre>
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    1. COWhat did your unit testing tell you? How about your integration testing, stress testing, or user acceptance testing? Or are you going to push this into production based on a few comments from some random Joes on the net. Your company must be an absolutely thrilling place to work at :-)
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    2. COWhat if **one** person sends 50 requests at once? Must others suffer from this?
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    3. COThis program is far from UAT, it is a 2nd contingency program
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