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copied!<p>OK, so this looks like a classic case of over optimization. Object creation isn't that expensive that you need to rewrite the same string buffer, especially if this is called every 300-400ms.</p> <p>I'll try to address every possible scenario: <strong>Exponential growth</strong> The above code is assigned to a new thread every 300ms but the list is enormous and takes over 300ms to serialize. If this is the case you are basically choking your resources and it is only a matter of time before the application crashes. If this is the case, you should see the CPU constantly rising. The solution would be to:</p> <ol> <li>Limit the number of threads that can run concurrently so you don't kill the application</li> <li>Concurrently build the json object and merge the result so building a single json takes less then 300ms.</li> </ol> <p><strong>Speedups</strong> OK, so the list isn't clonable which I'm assuming means it isn't really a list but rather some sort of queue implemented as a list interface. So leaving synchronization as is I would do this:</p> <pre><code>public static final int JSON_LENGTH = 250; //you probably know this public static String toJson(final List<QuotesData> quotesData) { jsonVal = new StringBuilder(JSON_LENGTH * quotesData.size()); jsonVal.append("{"); synchronized (quotesData) { for (QuotesData quote : quotesData) { jsonVal.append("\"").append(quote.getSymbol()).append("\":[{") .append("\"ask\":\"").append(quote.getAsk()).append("\",") .append("\"bid\":\"").append(quote.getBid()).append("\",") .append("\"time\":\"").append(quote.getDateTime()).append("\"}],"); } // much much faster than replace jsonVal.setCharAt(jsonVal.length()-1, '}'); return jsonVal.toString(); } } </code></pre> <p>Most of the changes are cosmetic, and I'm pretty sure that the JIT would already optimize them. Only difference I would do is use StringBuilder and create a new one each time and don't use <em>.replace()</em>. But to stress my point further unless you fit the first description (exponential growth) I doubt the problem is here. I would look at you list implementation first.</p>

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