分布式链路追踪：TraceIdFilter + MDC + Skywalking+MDC skywalking实现业务全局唯一号和skywalkingTraceID的整合
转载自博客：https://juejin.cn/post/7278498472860581925
https://juejin.cn/post/7278498472860581925
痛点 1. 查线上日志时，同一个 Pod 内多线程日志交错，很难追踪每个请求对应的日志信息。 2. 日志收集工具将多个 Pod 的日志收集到同一个数据库中后，情况就更加混乱不堪了。
TraceId + MDC
- 前端每次请求时，添加 X-App-Trace-Id 请求头，X-App-Trace-Id 值的生成方式可以选择【时间戳 + UUID】，保证 traceId 的唯一性。
- 后端在 TraceIdFilter 中取出 X-App-Trace-Id 的值：String traceId = httpServletRequest.getHeader(TRACE_ID_HEADER_KEY)。如果请求没有携带 X-App-Trace-Id 请求头，后端服务可以使用 UUID 或者 Snowflake 算法生成一个 traceId。
- 将 traceId 塞到 slf4j MDC 中：MDC.put(MDC_TRACE_ID_KEY, traceId)，在 logback pattern 中使用 %X{traceId} 占位符打印 traceId。
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest httpServletRequest = (HttpServletRequest) request; String traceId = httpServletRequest.getHeader(TRACE_ID_HEADER_KEY); if (StrUtil.isBlank(traceId)) { traceId = UUID.randomUUID().toString(); } MDC.put(MDC_TRACE_ID_KEY, traceId); try { chain.doFilter(request, response); } finally { MDC.remove(MDC_TRACE_ID_KEY); } }
<?xml version="1.0" encoding="UTF-8"?>
<configuration debug="false">
<property name="pattern" value="[%d{yyyy-MM-dd HH:mm:ss.SSS}] %-5level [%thread] %logger %line [%X{traceId}] [%tid] - %msg%n"/>
整合 Feign 发起服务间调用时，需要将 MDC 中的 traceId 传递到被调用服务。我们项目中统一使用 Feign Client，实现服务间的 HTTP 远程调用，在 Feign RequestInterceptor 中，取出 MDC 中的 traceId，塞到请求头中：requestTemplate.header(TRACE_ID_HEADER_KEY, MDC.get(MDC_TRACE_ID_KEY));
@Override
public void apply(RequestTemplate template) {
template.header(TRACE_ID_HEADER_KEY, MDC.get(MDC_TRACE_ID_KEY));
}
多线程适配
Please note that MDC as implemented by logback-classic assumes that values are placed into the MDC with moderate frequency. Also note that a child thread does not automatically inherit a copy of the mapped diagnostic context of its parent. 在子线程执行任务前，将父线程的 MDC 内容设置到子线程的 MDC 中；在子线程任务执行完成后，清除子线程 MDC 中的内容。 适配 JDK ThreadPoolExecutor：
public class MdcAwareThreadPoolExecutor extends ThreadPoolExecutor {
@Override
public void execute(Runnable command) {
Map<String, String> parentThreadContextMap = MDC.getCopyOfContextMap();
super.execute(MdcTaskUtils.adaptMdcRunnable(command, parentThreadContextMap));
}
适配 Spring TaskDecorator：
@Component
public class MdcAwareTaskDecorator implements TaskDecorator {
@Override
public Runnable decorate(Runnable runnable) {
Map<String, String> parentThreadContextMap = MDC.getCopyOfContextMap();
return MdcTaskUtils.adaptMdcRunnable(runnable, parentThreadContextMap);
}
MdcTaskUtils#adaptMdcRunnable()：采用装饰者模式，装饰原生的 Runnable runnable 对象，在原生 Runnable 对象执行前，将父线程的 MDC 设置到子线程中，在原生 Runnable 对象执行结束后，清除子线程 MDC 中的内容。
@Slf4j public abstract class MdcTaskUtils { public static Runnable adaptMdcRunnable(Runnable runnable, Map<String, String> parentThreadContextMap) { return () -> { log.debug("parentThreadContextMap: {}, currentThreadContextMap: {}", parentThreadContextMap, MDC.getCopyOfContextMap()); if (MapUtils.isEmpty(parentThreadContextMap) || !parentThreadContextMap.containsKey(MDC_TRACE_ID_KEY)) { log.debug("can not find a parentThreadContextMap, maybe task is fired using async or schedule task."); MDC.put(MDC_TRACE_ID_KEY, UUID.randomUUID().toString()); } else { MDC.put(MDC_TRACE_ID_KEY, parentThreadContextMap.get(MDC_TRACE_ID_KEY)); } try { runnable.run(); } finally { MDC.remove(MDC_TRACE_ID_KEY); } }; } }
整合 Skywalking
Skywalking 官方提供了对 logback 1.x 版本的适配：apm-toolkit-logback-1.x，可以在 logback 中打印 skywalking traceId，可以将 X-App-Trace-Id 和 skywalking traceId 结合起来，方便接口业务和性能问题的排查。
- layout 具体实现类选择 TraceIdPatternLogbackLayout。
- 在 logback pattern 中使用 %tid 打印 skywalking traceId。
<?xml version="1.0" encoding="UTF-8"?> <configuration debug="false"> <property name="pattern" value="[%d{yyyy-MM-dd HH:mm:ss.SSS}] %-5level [%thread] %logger %line [%X{traceId}] [%tid] - %msg%n"/> <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender"> <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder"> <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout"> <pattern>${pattern}</pattern> </layout> </encoder> </appender>
TraceIdPatternLogbackLayout 类初始化时，添加了两个 PatternConverter： 1. tid：使用 LogbackPatternConverter，将 %tid 占位符转换为 skywalking traceId。 2. sw_ctx：使用 LogbackSkyWalkingContextPatternConverter，将 %sw_ctx 占位符转换为 skywalking context。
public class TraceIdPatternLogbackLayout extends PatternLayout {
public TraceIdPatternLogbackLayout() {
}
static {
defaultConverterMap.put("tid", LogbackPatternConverter.class.getName());
defaultConverterMap.put("sw_ctx", LogbackSkyWalkingContextPatternConverter.class.getName());
}
}
LogbackPatternConverter#convert() 方法写死了返回 "TID: N/A"，这是怎么回事呢？
public class LogbackPatternConverter extends ClassicConverter {
public LogbackPatternConverter() {
}
public String convert(ILoggingEvent iLoggingEvent) {
return "TID: N/A";
}
}
启动 Java 应用时，指定 java agent 启动参数 -javaagent:-javaagent:/opt/tools/skywalking-agent.jar。skywalking agent 会代理 LogbackPatternConverter 类，重写 convert() 方法的逻辑。
package org.apache.skywalking.apm.toolkit.log.logback.v1.x;
import ch.qos.logback.classic.pattern.ClassicConverter;
import ch.qos.logback.classic.spi.ILoggingEvent;
import java.lang.reflect.Method;
import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.EnhancedInstance;
import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter;
import org.apache.skywalking.apm.toolkit.log.logback.v1.x.LogbackPatternConverter$auxiliary$pJ6Zrqzi;
public class LogbackPatternConverter
extends ClassicConverter
implements EnhancedInstance {
private volatile Object _$EnhancedClassField_ws;
public static volatile /* synthetic */ InstMethodsInter delegate$mo3but1;
private static final /* synthetic */ Method cachedValue$oeLgRjrq$u5j8qu3;
public String convert(ILoggingEvent iLoggingEvent) {
return (String)delegate$mo3but1.intercept(this, new Object[]{iLoggingEvent}, new LogbackPatternConverter$auxiliary$pJ6Zrqzi(this, iLoggingEvent), cachedValue$oeLgRjrq$u5j8qu3);
}
private /* synthetic */ String convert$original$T8InTdln(ILoggingEvent iLoggingEvent) {
/*34*/ return "TID: N/A";
}
@Override
public void setSkyWalkingDynamicField(Object object) {
this._$EnhancedClassField_ws = object;
}
@Override
public Object getSkyWalkingDynamicField() {
return this._$EnhancedClassField_ws;
}
static {
ClassLoader.getSystemClassLoader().loadClass("org.apache.skywalking.apm.dependencies.net.bytebuddy.dynamic.Nexus").getMethod("initialize", Class.class, Integer.TYPE).invoke(null, LogbackPatternConverter.class, -1942176692);
cachedValue$oeLgRjrq$u5j8qu3 = LogbackPatternConverter.class.getMethod("convert", ILoggingEvent.class);
}
final /* synthetic */ String convert$original$T8InTdln$accessor$oeLgRjrq(ILoggingEvent iLoggingEvent) {
return this.convert$original$T8InTdln(iLoggingEvent);
}
}
MDC 原理 MDC 在 slf4j-api jar 包中，MDC 是 slf4j 的规范，对 MDC 的所有操作都会落到 MDCAdapter 接口的方法上。
public class MDC {
static final String NULL_MDCA_URL = "http://www.slf4j.org/codes.html#null_MDCA";
static final String NO_STATIC_MDC_BINDER_URL = "http://www.slf4j.org/codes.html#no_static_mdc_binder";
static MDCAdapter mdcAdapter;
public static void put(String key, String val) throws IllegalArgumentException {
if (key == null) {
throw new IllegalArgumentException("key parameter cannot be null");
}
if (mdcAdapter == null) {
throw new IllegalStateException("MDCAdapter cannot be null. See also " + NULL_MDCA_URL);
}
mdcAdapter.put(key, val);
}
MDCAdapter 是 slf4j 提供的 MDC 适配器接口，也就是 MDC 的规范。任何日志框架想要使用 MDC 功能，需要遵守 MDCAdapter 接口接口规范，实现接口中的方法。
// This interface abstracts the service offered by various MDC implementations.
public interface MDCAdapter {
public void put(String key, String val);
public String get(String key);
Logback 日志框架提供了对 MDCAdapter 的适配：LogbackMDCAdapter，底层采用 ThreadLocal 实现。
public class LogbackMDCAdapter implements MDCAdapter { // The internal map is copied so as // We wish to avoid unnecessarily copying of the map. To ensure // efficient/timely copying, we have a variable keeping track of the last // operation. A copy is necessary on 'put' or 'remove' but only if the last // operation was a 'get'. Get operations never necessitate a copy nor // successive 'put/remove' operations, only a get followed by a 'put/remove' // requires copying the map. // See http://jira.qos.ch/browse/LOGBACK-620 for the original discussion. // We no longer use CopyOnInheritThreadLocal in order to solve LBCLASSIC-183 // Initially the contents of the thread local in parent and child threads // reference the same map. However, as soon as a thread invokes the put() // method, the maps diverge as they should. final ThreadLocal<Map<String, String>> copyOnThreadLocal = new ThreadLocal<Map<String, String>>(); private static final int WRITE_OPERATION = 1; private static final int MAP_COPY_OPERATION = 2; // keeps track of the last operation performed final ThreadLocal<Integer> lastOperation = new ThreadLocal<Integer>(); public void put(String key, String val) throws IllegalArgumentException { if (key == null) { throw new IllegalArgumentException("key cannot be null"); } Map<String, String> oldMap = copyOnThreadLocal.get(); Integer lastOp = getAndSetLastOperation(WRITE_OPERATION); if (wasLastOpReadOrNull(lastOp) || oldMap == null) { Map<String, String> newMap = duplicateAndInsertNewMap(oldMap); newMap.put(key, val); } else { oldMap.put(key, val); } } public String get(String key) { final Map<String, String> map = copyOnThreadLocal.get(); if ((map != null) && (key != null)) { return map.get(key); } else { return null; } }
Logback 占位符 PatternLayout 类初始化时，设置了 logback 常用占位符对应的 Converter。 java 代码解读 复制代码
public class PatternLayout extends PatternLayoutBase<ILoggingEvent> {
public static final Map<String, String> DEFAULT_CONVERTER_MAP = new HashMap<String, String>();
public static final Map<String, String> CONVERTER_CLASS_TO_KEY_MAP = new HashMap<String, String>();
/**
* @deprecated replaced by DEFAULT_CONVERTER_MAP
*/
public static final Map<String, String> defaultConverterMap = DEFAULT_CONVERTER_MAP;
public static final String HEADER_PREFIX = "#logback.classic pattern: ";
static {
DEFAULT_CONVERTER_MAP.putAll(Parser.DEFAULT_COMPOSITE_CONVERTER_MAP);
DEFAULT_CONVERTER_MAP.put("d", DateConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("date", DateConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(DateConverter.class.getName(), "date");
DEFAULT_CONVERTER_MAP.put("r", RelativeTimeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("relative", RelativeTimeConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(RelativeTimeConverter.class.getName(), "relative");
DEFAULT_CONVERTER_MAP.put("level", LevelConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("le", LevelConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("p", LevelConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(LevelConverter.class.getName(), "level");
DEFAULT_CONVERTER_MAP.put("t", ThreadConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("thread", ThreadConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(ThreadConverter.class.getName(), "thread");
DEFAULT_CONVERTER_MAP.put("lo", LoggerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("logger", LoggerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("c", LoggerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(LoggerConverter.class.getName(), "logger");
DEFAULT_CONVERTER_MAP.put("m", MessageConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("msg", MessageConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("message", MessageConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(MessageConverter.class.getName(), "message");
DEFAULT_CONVERTER_MAP.put("C", ClassOfCallerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("class", ClassOfCallerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(ClassOfCallerConverter.class.getName(), "class");
DEFAULT_CONVERTER_MAP.put("M", MethodOfCallerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("method", MethodOfCallerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(MethodOfCallerConverter.class.getName(), "method");
DEFAULT_CONVERTER_MAP.put("L", LineOfCallerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("line", LineOfCallerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(LineOfCallerConverter.class.getName(), "line");
DEFAULT_CONVERTER_MAP.put("F", FileOfCallerConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("file", FileOfCallerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(FileOfCallerConverter.class.getName(), "file");
DEFAULT_CONVERTER_MAP.put("X", MDCConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("mdc", MDCConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("ex", ThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("exception", ThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("rEx", RootCauseFirstThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("rootException", RootCauseFirstThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("throwable", ThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("xEx", ExtendedThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("xException", ExtendedThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("xThrowable", ExtendedThrowableProxyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("nopex", NopThrowableInformationConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("nopexception", NopThrowableInformationConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("cn", ContextNameConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("contextName", ContextNameConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(ContextNameConverter.class.getName(), "contextName");
DEFAULT_CONVERTER_MAP.put("caller", CallerDataConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(CallerDataConverter.class.getName(), "caller");
DEFAULT_CONVERTER_MAP.put("marker", MarkerConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(MarkerConverter.class.getName(), "marker");
DEFAULT_CONVERTER_MAP.put("property", PropertyConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("n", LineSeparatorConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("black", BlackCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("red", RedCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("green", GreenCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("yellow", YellowCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("blue", BlueCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("magenta", MagentaCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("cyan", CyanCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("white", WhiteCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("gray", GrayCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldRed", BoldRedCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldGreen", BoldGreenCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldYellow", BoldYellowCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldBlue", BoldBlueCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldMagenta", BoldMagentaCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldCyan", BoldCyanCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("boldWhite", BoldWhiteCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("highlight", HighlightingCompositeConverter.class.getName());
DEFAULT_CONVERTER_MAP.put("lsn", LocalSequenceNumberConverter.class.getName());
CONVERTER_CLASS_TO_KEY_MAP.put(LocalSequenceNumberConverter.class.getName(), "lsn");
DEFAULT_CONVERTER_MAP.put("prefix", PrefixCompositeConverter.class.getName());
}
ThreadConverter：将 %thread 占位符转换为 logger 线程。
public class ThreadConverter extends ClassicConverter {
public String convert(ILoggingEvent event) {
return event.getThreadName();
}
在 PatternLayout 中，默认添加了对 MDC 的支持，可以将 %X{key} 或者 %mdc{key} 占位符转换为 MDC.get(key)。
DEFAULT_CONVERTER_MAP.put("X", MDCConverter.class.getName()); DEFAULT_CONVERTER_MAP.put("mdc", MDCConverter.class.getName());
MDCConverter 为何可以将 %X{traceId} 或者 %mdc{traceId} 占位符转换为 MDC.get("traceId") ？
在程序启动时，ch.qos.logback.core.pattern.parser.Compiler#compile() 会解析用户配置的 pattern 表达式，得到 pattern 中需要动态解析的占位符，比如 %d{yyyy-MM-dd HH:mm:ss.SSS}，%X{traceId}。将这些动态占位符传递给 DynamicConverter#optionList 字段（MDCConverter 本质就是 DynamicConverter），optionList 字段包含程序要处理的占位符名称，比如 traceId。
程序启动时，logback 进行 Convert 初始化，会调用 MDCConverter#start() 方法，将成员变量 private String key 的值设置为 traceId（MDCConverter#getFirstOption() 返回用户配置的 traceId）。
public class MDCConverter extends ClassicConverter { private String key; private String defaultValue = ""; @Override public void start() { String[] keyInfo = extractDefaultReplacement(getFirstOption()); key = keyInfo[0]; if (keyInfo[1] != null) { defaultValue = keyInfo[1]; } super.start(); } @Override public String convert(ILoggingEvent event) { Map<String, String> mdcPropertyMap = event.getMDCPropertyMap(); if (mdcPropertyMap == null) { return defaultValue; } if (key == null) { return outputMDCForAllKeys(mdcPropertyMap); } else { String value = mdcPropertyMap.get(key); if (value != null) { return value; } else { return defaultValue; } } }
ILoggingEvent 接口的实现类 LoggingEvent 中，对 MDCAdapter 做了适配：
public class LoggingEvent implements ILoggingEvent {
public Map<String, String> getMDCPropertyMap() {
// populate mdcPropertyMap if null
if (mdcPropertyMap == null) {
MDCAdapter mdc = MDC.getMDCAdapter();
if (mdc instanceof LogbackMDCAdapter)
mdcPropertyMap = ((LogbackMDCAdapter) mdc).getPropertyMap();
else
mdcPropertyMap = mdc.getCopyOfContextMap();
}
// mdcPropertyMap still null, use emptyMap()
if (mdcPropertyMap == null)
mdcPropertyMap = Collections.emptyMap();
return mdcPropertyMap;
}
posted on 2024-12-19 14:48 luzhouxiaoshuai 阅读(3) 评论(0) 编辑 收藏 举报
