修改SimpleDateFormat format方法线程不安全问题

Author: yikangfeng

sentinel-core/src/main/java/com/alibaba/csp/sentinel/log/CspFormatter.java

@@ -28,27 +28,33 @@
  */
 class CspFormatter extends Formatter {
 
-    private final DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+	private final ThreadLocal<SimpleDateFormat> dateFormatThreadLocal = new ThreadLocal<SimpleDateFormat>() {
+		@Override
+		public SimpleDateFormat initialValue() {
+			return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+		}
+	};
 
-    @Override
-    public String format(LogRecord record) {
-        StringBuilder builder = new StringBuilder(1000);
-        builder.append(df.format(new Date(record.getMillis()))).append(" ");
-        builder.append(formatMessage(record));
+	@Override
+	public String format(LogRecord record) {
+		final DateFormat df = dateFormatThreadLocal.get();
+		StringBuilder builder = new StringBuilder(1000);
+		builder.append(df.format(new Date(record.getMillis()))).append(" ");
+		builder.append(formatMessage(record));
 
-        String throwable = "";
-        if (record.getThrown() != null) {
-            StringWriter sw = new StringWriter();
-            PrintWriter pw = new PrintWriter(sw);
-            pw.println();
-            record.getThrown().printStackTrace(pw);
-            pw.close();
-            throwable = sw.toString();
-        }
-        builder.append(throwable);
-        if ("".equals(throwable)) {
-            builder.append("\n");
-        }
-        return builder.toString();
-    }
+		String throwable = "";
+		if (record.getThrown() != null) {
+			StringWriter sw = new StringWriter();
+			PrintWriter pw = new PrintWriter(sw);
+			pw.println();
+			record.getThrown().printStackTrace(pw);
+			pw.close();
+			throwable = sw.toString();
+		}
+		builder.append(throwable);
+		if ("".equals(throwable)) {
+			builder.append("\n");
+		}
+		return builder.toString();
+	}
 }