日志文件大小与 logback 中的 SizeBasedTriggerPolicy 不一致

如何解决日志文件大小与 logback 中的 SizeBasedTriggerPolicy 不一致

我使用带有 FixedWindowRollingPolicy 和 SizeBasedTriggerPolicy 的 RollingFileAppender 定义了 getLoggerWithAppender() API。日志文件大小设置为 5000（用于测试目的）。最大索引设置为 10。但是，当我运行测试用例时，它会生成文件大小不一致的日志文件，这是意料之中的。我尝试按照 SizeBasedTriggeringPolicy limit is not working 中的示例进行操作，但没有帮助。

package main 

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.contrib.jackson.JacksonJsonFormatter;
import ch.qos.logback.contrib.json.classic.JsonLayout;
import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
import ch.qos.logback.core.rolling.FixedWindowRollingPolicy;
import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy;
import ch.qos.logback.core.util.FileSize;
import org.slf4j.LoggerFactory;

import java.io.File;

class JavaLogger {
  public static Logger getLoggerWithAppende(String loggerName) {
      
    LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
    RollingFileAppender fileAppender = new RollingFileAppender();
    fileAppender.setContext(loggerContext);
    fileAppender.setFile("./log/" + File.separator + "logfile.log");
    fileAppender.setAppend(false);
  
    // Rolling policy
    FixedWindowRollingPolicy rollingPolicy = new FixedWindowRollingPolicy();
    rollingPolicy.setContext(loggerContext);
    rollingPolicy.setFileNamePattern("./log/" + File.separator + "logfile-%i.log");
    rollingPolicy.setParent(fileAppender);
    rollingPolicy.start();
    rollingPolicy.setMinIndex(1);
    rollingPolicy.setMaxIndex(10);
    fileAppender.setRollingPolicy(rollingPolicy);
  
    // Rollover trigger policy
    SizeBasedTriggeringPolicy triggeringPolicy = new SizeBasedTriggeringPolicy();
    triggeringPolicy.setContext(loggerContext);
    triggeringPolicy.setMaxFileSize(FileSize.valueOf("5000"));
    triggeringPolicy.start();
    fileAppender.setTriggeringPolicy(triggeringPolicy);
  
    // JSON log message encoder
    LayoutWrappingEncoder layoutEncoder = new LayoutWrappingEncoder();
    JacksonJsonFormatter jacksonJsonFormatter = new JacksonJsonFormatter();
    JsonLayout jsonLayout = new JsonLayout();
    jsonLayout.setTimestampFormat("yyyy-MM-dd HH:mm:ss.SSS");
    jsonLayout.setContext(loggerContext);
    jsonLayout.setAppendLineSeparator(true);
    jsonLayout.setIncludeException(true);
    jsonLayout.setIncludeMDC(true);
    jsonLayout.setJsonFormatter(jacksonJsonFormatter);
    layoutEncoder.setLayout(jsonLayout);
    layoutEncoder.setContext(loggerContext);
    layoutEncoder.start();
  
    fileAppender.setEncoder(layoutEncoder);
    fileAppender.start();
  
    // configures  logger
    Logger logger = loggerContext.getLogger(loggerName);
    logger.setLevel(Level.ALL);
    logger.addAppender(fileAppender);
    logger.setAdditive(false);
    return logger;
  }
}

测试程序如下。

package main 

import ch.qos.logback.classic.Logger;

public class LoggerMain {

    public static void main(String[] args) {
        Logger logger = JavaLogger.getLoggerWithAppende("test");

        for (int i = 0; i < 1000; i++) {
            logger.debug("This is debug1 message");
            logger.error("This is error1 message");
            logger.warn("This is warn1 message");
            logger.trace("This is trace1 message");
            logger.info("This is info1 message");
        }
    }
}

它生成的输出日志文件大小是。每个日志文件大小应该在 5K 左右，但正在创建的日志文件大小多种多样。

ls -lrt
total 1424
-rw-r--r--  1 user  staff    8959 Mar 13 01:47 logfile-7.log
-rw-r--r--  1 user  staff    9102 Mar 13 01:47 logfile-6.log
-rw-r--r--  1 user  staff   18200 Mar 13 01:47 logfile-5.log
-rw-r--r--  1 user  staff   36404 Mar 13 01:47 logfile-4.log
-rw-r--r--  1 user  staff   72806 Mar 13 01:47 logfile-3.log
-rw-r--r--  1 user  staff  145614 Mar 13 01:47 logfile-2.log
-rw-r--r--  1 user  staff  291224 Mar 13 01:47 logfile-1.log
-rw-r--r--  1 user  staff  128691 Mar 13 01:47 logfile.log