changed fileappender to use writeStream instead of fs.write, tests don't work

lib/log4js.js

@@ -283,16 +283,20 @@ function consoleAppender (layout) {
  */
 function fileAppender (file, layout, logSize, numBackups, filePollInterval) {
     layout = layout || layouts.basicLayout;
-    //syncs are generally bad, but we need
+    var logFile = fs.createWriteStream(file, { flags: 'a', mode: 0644, encoding: 'utf8' });
-    //the file to be open before we start doing any writing.
-    var logFile = fs.openSync(file, 'a', 0644);
 
     if (logSize > 0) {
         setupLogRolling(logFile, file, logSize, numBackups || 5, (filePollInterval * 1000) || 30000);
     }
 
+    //close the file on process exit, otherwise the process won't die.
+    process.on('exit', function() {
+        logFile.end();
+        logFile.destroySoon();
+    });
+
     return function(loggingEvent) {
-	fs.write(logFile, layout(loggingEvent)+'\n', null, "utf8");
+	logFile.write(layout(loggingEvent)+'\n');
     };
 }
 
@@ -312,9 +316,9 @@ function setupLogRolling (logFile, filename, logSize, numBackups, filePollInterv
 }
 
 function rollThatLog (logFile, filename, numBackups) {
-    //doing all of this fs stuff sync, because I don't want to lose any log events.
     //first close the current one.
-    fs.closeSync(logFile);
+    logFile.end();
+    logFile.destroySoon();
     //roll the backups (rename file.n-1 to file.n, where n <= numBackups)
     for (var i=numBackups; i > 0; i--) {
         if (i > 1) {
@@ -326,7 +330,7 @@ function rollThatLog (logFile, filename, numBackups) {
         }
     }
     //open it up again
-    logFile = fs.openSync(filename, 'a', 0644);
+    logFile = fs.createWriteStream(filename, { flags: 'a', mode: 0644, encoding: "utf8" });
 }
 
 function fileExists (filename) {

memory-test.js

@@ -0,0 +1,37 @@
+var log4js = require('./lib/log4js')
+, logger
+, usage
+, i;
+
+log4js.configure(
+    {
+        appenders: [
+            {
+                category: "memory-test"
+              , type: "file"
+              , filename: "memory-test.log"
+            },
+            {
+                type: "console"
+              , category: "memory-usage"
+            },
+            {
+                type: "file"
+              , filename: "memory-usage.log"
+              , category: "memory-usage"
+              , layout: {
+                  type: "messagePassThrough"
+              }
+            }
+        ]
+    }
+);
+logger = log4js.getLogger("memory-test");
+usage = log4js.getLogger("memory-usage");
+
+for (i=0; i < 1000000; i++) {
+    if ( (i % 5000) === 0) {
+        usage.info("%d %d", i, process.memoryUsage().rss);
+    }
+    logger.info("Doing something.");
+}