问题描述
Log4j2不会重新创建日志文件.例如，粗心的管理员已删除了应用当前编写自己的日志的日志文件.
实际结果:日志未写入文件.
想要的结果:log4j2在首次尝试写入文件后重新创建文件并继续使用该文件.
Log4j2 does not recreate log files if they were deleted in runtime. For example, careless admin have removed log-files where app currently write own logs.
Actual result: logs doesn't write to file.
Wanted result: log4j2 recreate file after first attempt to write into it and continue to work with this file.
通过cron或其他方式进行的手动重新创建无法正常工作，因为log4j2会记住"文件的文件描述符，并且即使删除了旧文件并创建了新文件也可以继续使用它.
Manual recreating by cron or somehow else is not working because log4j2 "remembers" file descriptor of file and continiue to work with it even after old file was deleted and new was created.
在StackOverflow上，我仅找到一种解决方法( https://stackoverflow.com/a/51593404/5747662 )看起来像这样:
On the StackOverflow I found only one workaround (https://stackoverflow.com/a/51593404/5747662) and it looks like this:
package org.apache.log4j;
import java.io.File;
import org.apache.log4j.spi.LoggingEvent;
public class ModifiedRollingFileAppender extends RollingFileAppender {
@Override
public void append(LoggingEvent event) {
checkLogFileExist();
super.append(event);
}
private void checkLogFileExist(){
File logFile = new File(super.fileName);
if (!logFile.exists()) {
this.activateOptions();
}
}
}
我不喜欢它是因为:
1)慢"一点
每次编写事件时，我们还将执行checkLogFileExist()并检查文件系统中的文件.
2)它不适用于Log4j2
Log4j2中断中没有方法activateOptions().
那么有人会遇到同样的问题吗?你怎么解决的?
I don't like it beсause:
1) It "little bit" slow
Each time when we will write event we will also execute checkLogFileExist() and check file in filesystem.
2) It doesn't works for Log4j2
There is no method activateOptions() in Log4j2 infractucture.
So does anybody faced with same problem? How do you solved it?
更新
我尝试初始化触发策略"以手动翻转"已删除的文件，但是它对我不起作用.
我的代码:
UPDATE
I have tried to initialyze Triggering Policy to manually "rollover" deleted file, but it's not working for me.
My code:
final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
// loggerName is name of logger which should work with the file has been deleted.
LoggerConfig loggerConfig = ctx.getConfiguration().getLoggerConfig(loggerName);
// I also know what appender (appenderName) should work with this file.
RollingFileAppender appender = (RollingFileAppender) loggerConfig.getAppenders().get(appenderName);
appender.getTriggeringPolicy().initialize(appender.getManager());
也是我的配置:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="ERROR">
<Appenders>
<RollingFile name="FILE_LOG">
<FileName>../log/temp/server.log</FileName>
<FilePattern>../log/server/SERVER_%d{yyyy-MM-dd-hh-mm}.log</FilePattern>
<PatternLayout pattern="%d{dd.MM.yyyy HH:mm:ss} [%t] %-5level %msg%n"/>
<Policies>
<SizeBasedTriggeringPolicy size="100 MB" />
</Policies>
</RollingFile>
<RollingFile name="OUTPUT_LOG">
<FileName>../log/temp/output.log</FileName>
<FilePattern>../log/output/OUTPUT_%d{yyyy-MM-dd-hh-mm}.log</FilePattern>
<PatternLayout>
<Pattern>%d{dd.MM.yyyy HH:mm:ss} %msg</Pattern>
</PatternLayout>
<Policies>
<CronTriggeringPolicy schedule="0 0 * * * ?"/>
<OnStartupTriggeringPolicy />
<SizeBasedTriggeringPolicy size="50 MB" />
</Policies>
</RollingFile>
</Appenders>
<Loggers>
<Logger name="OUTPUT" level="debug" additivity="false">
<AppenderRef ref="OUTPUT_LOG" />
</Logger>
<Root level="debug">
<AppenderRef ref="FILE_LOG" />
</Root>
</Loggers>
</Configuration>
推荐答案
我终于找到了解决方案.谢谢@Alexander的留言提示.
I'm finally find the solution. Thanx @Alexander in comments for tip.
简短:我们可以在检测到文件删除时手动初始化翻转过程.
Short: We can manually initialize rollover process when detect file deletition.
更长:
我是这样实现的:
1)创建FileWatchService，它将(1)订阅您的日志文件夹中的日志文件删除事件，并且(2)在这些事件发生时通知您.可以通过java.nio.file.WatchService( https://docs.oracle.com/javase/tutorial/essential/io/notification.html ).我将在下面提供我的代码.
2)创建其他一些类，该类将在FileWatchService通知文件删除时初始化过渡.我还将在下面提供我的完整代码，但主要的魔术将通过这种方式发生:
Longer:
I implement it this way:
1) Create FileWatchService which will (1) subscribe for the log-file deletiiton events in your log folder and (2) notify you when these events will occur. It can be done by java.nio.file.WatchService (https://docs.oracle.com/javase/tutorial/essential/io/notification.html). I will provide my code below.
2) Create some other class which will initialize rollover when FileWatchService will notify about file deletition. I'm also will provide my full code below, but main magic will be occur this way:
final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
// You should know only appender name.
RollingFileAppender appender = (RollingFileAppender) ctx.getConfiguration().getAppenders().get(appenderName);
if (appender != null) {
// Manually start rollover logic.
appender.getManager().rollover();
}
我的代码看起来像这样(不理想，但对我有用):FileWatchService:
My code looks like this (not ideal but it's working for me):FileWatchService:
public class FileWatchService implements Runnable {
private final org.apache.logging.log4j.Logger logger = LogManager.getLogger(FileWatchService.class);
private WatchService watchService = null;
private Map<WatchKey,Path> keys = null;
private String tempPath;
public FileWatchService(String tempPath) {
try {
this.watchService = FileSystems.getDefault().newWatchService();
this.keys = new HashMap<WatchKey,Path>();
this.tempPath = tempPath;
Path path = Paths.get(tempPath);
register(path);
logger.info("Watch service has been initiated.");
}
catch (Exception e) {
logger.error("The error occurred in process of registering watch service", e);
}
}
// Method which register folder to watch service.
private void register(Path tempPath) throws IOException {
logger.debug("Registering folder {} for watching.", tempPath.getFileName());
// Registering only for delete events.
WatchKey key = tempPath.register(watchService, ENTRY_DELETE);
keys.put(key, tempPath);
}
@Override
public void run() {
try {
Thread.currentThread().setName("FileWatchService");
this.processEvents();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private void processEvents() throws InterruptedException {
WatchKey key;
// Waiting until event occur.
while ((key = watchService.take()) != null) {
// Poll all events when event occur.
for (WatchEvent<?> event : key.pollEvents()) {
// Getting type of event - delete, modify or create.
WatchEvent.Kind kind = event.kind();
// We are interested only for delete events.
if (kind == ENTRY_DELETE) {
// Sending "notification" to appender watcher service.
logger.debug("Received event about file deletion. File: {}", event.context());
AppenderWatcher.hadleLogFileDeletionEvent(this.tempPath + event.context());
}
}
key.reset();
}
}
}
另一个用于初始化翻转的类(我称之为AppenderWatcher):
Another class for initilize rollover (I have called it AppenderWatcher):
public class AppenderWatcher {
private static final org.apache.logging.log4j.Logger logger = LogManager.getLogger(AppenderWatcher.class);
public static void hadleLogFileDeletionEvent(String logFile) {
File file = new File(logFile);
if (!checkFileExist(file)) {
logger.info("File {} is not exist. Starting manual rollover...", file.toString());
// Getting possible appender name by log-file.
String appenderName = getAppenderNameByFileName(logFile);
// Getting appender from list of all appender
RollingFileAppender appender = (RollingFileAppender) getAppender(appenderName);
if (appender != null) {
// Manually start rollover logic.
appender.getManager().rollover();
logger.info("Rollover finished");
}
else {
logger.error("Can't get appender {}. Please, check lo4j2 config.", appenderName);
}
} else {
logger.warn("Received notification what file {} was deleted, but it exist.", file.getAbsolutePath());
}
}
// Method which checks is file exist. It need to prevent conflicts with Log4J rolling file logic.
// When Log4j rotate file it deletes it first and create after.
private static boolean checkFileExist(File logFile) {
return logFile.exists();
}
// Method which gets appender by name from list of all configured appenders.
private static Appender getAppender(String appenderName) {
final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
return ctx.getConfiguration().getAppenders().get(appenderName);
}
// Method which returns name of appender by log file name.
// ===Here I'm explaining some customer specific moments of log4j config.
private static String getAppenderNameByFileName(String fileName) {
return getLoggerNameByFileName(fileName) + "_LOG";
}
// This method fully customer specific.
private static String getLoggerNameByFileName(String fileName) {
// File name looks like "../log/temp/uber.log" (example).
String[] parts = fileName.split("/");
// Last part should look like "uber.log"
String lastPart = parts[parts.length - 1];
// We need only "uber" part.
String componentName = lastPart.substring(0, lastPart.indexOf("."));
return componentName.toUpperCase();
}
}
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