Mark 的滿紙方糖言

Jobs

SIGHUP
- 默认动作：Terminate
- 可能动作：Terminate, Ignore, Function call
当检测到 hangup 时，UART 驱动会向整个 session 发送 SIGHUP 信号。正常情况下，这会 kill 掉所有进程。某些程序，例如 nohup(1) 和 screen(1)，会从他们的 session（和 TTY）中 detach 出来，因此这些程序的子进程无法关注到 hangup 事件。

内置 Classloader

The class loader delegation model

Class loaders load classes and resources present on their respective classpath:

System or application class loaders load classes from the application classpath
Extension class loaders search on the Extension classpath (JRE/lib/ext)
Bootstrap class loader looks on the Bootstrap classpath (JRE/lib/rt.jar)

We can customize the default class loading behavior as well. We can explicitly specify the class loader while loading a class dynamically.

However, we should note that if we load the same class from different types of class loaders, these will be seen as different resources by the JVM.

Opentelemetry Java Agent 浅度解构

📅 2021年04月01日 · ☕ 2 分钟

https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/docs/contributing/javaagent-jar-components.md

Agent initialization sequence

Agent classloader state

Conf

Creating spans around methods with otel.instrumentation.methods.include

Ref: https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/docs/manual-instrumentation.md

Format is "java -Dotel.instrumentation.methods.include=my.package.MyClass1[method1,method2];my.package.MyClass2[method3]"

Classloader

[arthas@16908]$ classloader -t
+-BootstrapClassLoader                                                                                                 
+-io.opentelemetry.javaagent.bootstrap.AgentClassLoader@379619aa                                                       
+-sun.misc.Launcher$ExtClassLoader@41fa769c                                                                            
  +-com.taobao.arthas.agent.ArthasClassloader@3697b340                                                                 
  +-sun.misc.Launcher$AppClassLoader@18b4aac2                                                                          
    +-java.net.URLClassLoader@71b2d611                                                                                 
    +-java.net.URLClassLoader@69cd1085                                                                                 
    | +-WebAppClassLoader=266661735@fe4ef67                                                                            
    | | +-com.mycom.sig.foundation.servicediscovery.ExtendedClassLoader@573f7aae                                    
    | +-WebAppClassLoader=Server Initiated@1ccb04b3                                                                    
    | | +-com.mycom.sig.foundation.servicediscovery.ExtendedClassLoader@4b3b9a06                                    
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@73cb9ccb                                                                
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@7c380e94                                                                
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@69ec5d1f                                                                
    | +-WebAppClassLoader=OAuth Server@10d98940                                                                        
    | | +-com.mycom.ece.common.svcfinder.ExtendedClassLoader@3528968e                                               
    | | +-com.mycom.sig.foundation.servicediscovery.ExtendedClassLoader@2919aff3                                    
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@1b0e6bac                                                                
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@2f12d8d1                                                                
    | | +-jnr.ffi.provider.jffi.AsmClassLoader@73123f21                                                                
    | +-WebAppClassLoader=1133988396@43974a2c                                                                          
    |   +-com.mycom.sig.foundation.servicediscovery.ExtendedClassLoader@39d87c5f                                    
    +-java.net.URLClassLoader@1b4c457c                                                                                 
    +-java.net.URLClassLoader@3a477cf5                                                                                 
Affect(row-cnt:24) cost in 31 ms.

[arthas@16908]$ classloader
 name                                                              numberOfInstances  loadedCountTotal                 
 org.eclipse.jetty.webapp.WebAppClassLoader                        4                  24687                            
 BootstrapClassLoader                                              1                  4341                             
 io.opentelemetry.javaagent.bootstrap.AgentClassLoader             1                  3502                             
 com.taobao.arthas.agent.ArthasClassloader                         1                  1430                             
 java.net.URLClassLoader                                           4                  1252                             
 sun.misc.Launcher$AppClassLoader                                  1                  570                              
 sun.reflect.DelegatingClassLoader                                 378                378                              
 sun.misc.Launcher$ExtClassLoader                                  1                  56                               
 jnr.ffi.provider.jffi.AsmClassLoader                              6                  8                                
 com.mycom.sig.foundation.servicediscovery.ExtendedClassLoader  4                  6                                
 com.mycom.ece.common.svcfinder.ExtendedClassLoader             1                  1

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[arthas@16908]$ jad -c 1ccb04b3 com.mycom.jee.abc.client.service.payload.ClientResponse setProjectName

ClassLoader:                                                                                                           
+-WebAppClassLoader=Server Initiated@1ccb04b3                                                                          
  +-java.net.URLClassLoader@69cd1085                                                                                   
    +-sun.misc.Launcher$AppClassLoader@18b4aac2                                                                        
      +-sun.misc.Launcher$ExtClassLoader@41fa769c                                                                      

Location:                                                                                                              
/var/lib/modules/DP-OAuth-Traffic/tmp/server-initiated-aa-war.war/webapp/WEB-INF/lib/clients-api-3.19.5.jar            

            public void setProjectName(String string) {                                                                
                StackTraceElement[] stackTraceElementArray;
/*729*/         Context context = null;                                                                                
                Scope scope = null;               
                try {                                                                                                  
                    stackTraceElementArray = Thread.currentThread().getStackTrace();                                                                                                                                                          
                    context = MethodTracer.tracer().startSpan(ClientResponse.class.getMethod("setProjectName", String.class), stackTraceElementArray, new Object[]{string});
                    if (context != null) {
                        scope = context.makeCurrent();
                    }
                }
                catch (Throwable throwable) {
                    try {
                        LoggerFactory.getLogger(ExceptionLogger.class).debug("Failed to handle exception in instrumentation for com.mycom.jee.abc.client.service.payload.ClientResponse on sun.misc.Launcher$AppClassLoader@18b4aac2", thr$
wable);
                    }
                    catch (Throwable throwable2) {
                    }
                }
                stackTraceElementArray = this;
                String projectName = string;
                try {
                    this.projectName = projectName;
                    stackTraceElementArray = null;
                }
                catch (Throwable throwable) {
                    // empty catch block
                }
                try {
                    if (context != null) {
                        scope.close();
                        if (stackTraceElementArray != null) {
                            MethodTracer.tracer().endExceptionally(context, (Throwable)stackTraceElementArray);
                        } else {
                            Span span = Span.fromContext(context);
                            span.setAttribute(MethodTracer.JAVA_METHOD_RETURN.getKey(), null == null ? "null" : ((Object)null).toString());
                            MethodTracer.tracer().end(context);
                        }
                    }
                }
                catch (Throwable throwable) {
                    try {
                        LoggerFactory.getLogger(ExceptionLogger.class).debug("Failed to handle exception in instrumentation for com.mycom.jee.abc.client.service.payload.ClientResponse on sun.misc.Launcher$AppClassLoader@18b4aac2", thro
wable);
                    }
                    catch (Throwable throwable3) {
                    }
                }
                if (stackTraceElementArray != null) {
                    throw stackTraceElementArray;
                }
            }

[arthas@16908]$ sc io.opentelemetry.javaagent.instrumentation.methods.MethodInstrumentationModule
io.opentelemetry.javaagent.instrumentation.methods.MethodInstrumentationModule
Affect(row-cnt:1) cost in 54 ms.
[arthas@16908]$ sc -d io.opentelemetry.javaagent.instrumentation.methods.MethodInstrumentationModule
 class-info        io.opentelemetry.javaagent.instrumentation.methods.MethodInstrumentationModule                      
 code-source       /                                                                                                   
 name              io.opentelemetry.javaagent.instrumentation.methods.MethodInstrumentationModule                      
 isInterface       false                                                                                               
 isAnnotation      false                                                                                               
 isEnum            false                                                                                               
 isAnonymousClass  false                                                                                               
 isArray           false                                                                                               
 isLocalClass      false                                                                                               
 isMemberClass     false                                                                                               
 isPrimitive       false                                                                                               
 isSynthetic       false                                                                                               
 simple-name       MethodInstrumentationModule                                                                         
 modifier          public                                                                                              
 annotation                                                                                                            
 interfaces                                                                                                            
 super-class       +-io.opentelemetry.javaagent.tooling.InstrumentationModule                                          
                     +-java.lang.Object                                                                                
 class-loader      +-io.opentelemetry.javaagent.bootstrap.AgentClassLoader@379619aa                                    
 classLoaderHash   379619aa

[arthas@16908]$ sc -d io.opentelemetry.javaagent.instrumentation.methods.MethodTracer
 class-info        io.opentelemetry.javaagent.instrumentation.methods.MethodTracer                                     
 code-source                                                                                                           
 name              io.opentelemetry.javaagent.instrumentation.methods.MethodTracer                                     
 isInterface       false                                                                                               
 isAnnotation      false                                                                                               
 isEnum            false                                                                                               
 isAnonymousClass  false                                                                                               
 isArray           false                                                                                               
 isLocalClass      false                                                                                               
 isMemberClass     false                                                                                               
 isPrimitive       false                                                                                               
 isSynthetic       false                                                                                               
 simple-name       MethodTracer                                                                                        
 modifier          public                                                                                              
 annotation                                                                                                            
 interfaces                                                                                                            
 super-class       +-io.opentelemetry.javaagent.shaded.instrumentation.api.tracer.BaseTracer                           
                     +-java.lang.Object                                                                                
 class-loader      +-WebAppClassLoader=Server Initiated@1ccb04b3                                                       
                     +-java.net.URLClassLoader@69cd1085                                                                
                       +-sun.misc.Launcher$AppClassLoader@18b4aac2                                                     
                         +-sun.misc.Launcher$ExtClassLoader@41fa769c                                                   
 classLoaderHash   1ccb04b3                                                                                            

 class-info        io.opentelemetry.javaagent.instrumentation.methods.MethodTracer                                     
 code-source                                                                                                           
 name              io.opentelemetry.javaagent.instrumentation.methods.MethodTracer                                     
 isInterface       false                                                                                               
 isAnnotation      false                                                                                               
 isEnum            false                                                                                               
 isAnonymousClass  false                                                                                               
 isArray           false                                                                                               
 isLocalClass      false                                                                                               
 isMemberClass     false                                                                                               
 isPrimitive       false                                                                                               
 isSynthetic       false                                                                                               
 simple-name       MethodTracer                                                                                        
 modifier          public                                                                                              
 annotation                                                                                                            
 interfaces                                                                                                            
 super-class       +-io.opentelemetry.javaagent.shaded.instrumentation.api.tracer.BaseTracer                           
                     +-java.lang.Object                                                                                
 class-loader      +-WebAppClassLoader=OAuth Server@10d98940                                                           
                     +-java.net.URLClassLoader@69cd1085                                                                
                       +-sun.misc.Launcher$AppClassLoader@18b4aac2                                                     
                         +-sun.misc.Launcher$ExtClassLoader@41fa769c                                                   
 classLoaderHash   10d98940

shaded

io.opentelemetry.instrumentation.api.config.Config
->
sc -d io.opentelemetry.javaagent.shaded.instrumentation.api.config.Config

[arthas@16908]$ sc -d io.opentelemetry.javaagent.shaded.instrumentation.api.config.Config                                                                                            

 class-info        io.opentelemetry.javaagent.shaded.instrumentation.api.config.Config                                 
 code-source                                                                                                           
 name              io.opentelemetry.javaagent.shaded.instrumentation.api.config.Config                                 
 isInterface       false                                                                                               
 isAnnotation      false                                                                                               
 isEnum            false                                                                                               
 isAnonymousClass  false                                                                                               
 isArray           false                                                                                               
 isLocalClass      false                                                                                               
 isMemberClass     false                                                                                               
 isPrimitive       false                                                                                               
 isSynthetic       false                                                                                               
 simple-name       Config                                                                                              
 modifier          abstract,public                                                                                     
 annotation                                                                                                            
 interfaces                                                                                                            
 super-class       +-java.lang.Object                                                                                  
 class-loader                                                                                                          
 classLoaderHash   null

Custom Resource 的入口

请求是这样分发到 api 扩展点的：

例如我们有（Custom Resource）CR

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apiVersion: cnat.programming-kubernetes.info/v1alpha1
kind: At
metadata:
  name: example-at
spec:
  schedule: "2019-07-03T02:00:00Z"
status:
  phase: "pending"

相应的 CustomResourceDefinition (CRD) 会是这样：

API 入口

Client Sets

接收变更通知和缓存（Informers and Caching）

Client Sets可以 watch 变更，但一般我们用更高级的 Informers，因为它有缓存、索引等功能。

Lister ：被应用调用，返回缓存中的数据列表
Informer：监听器

Informer 有两个功能

Concept

umbrella chart

you can also create a chart with dependencies to other charts (a.k.a. umbrella chart) which are completely external using the requirements.yaml file.

versioning

Simple 1-1 versioning

Synced versions in Helm

Chart versus application versioning

Independent Helm versioning

参考

https://codefresh.io/docs/docs/new-helm/helm-best-practices/

前言

最近由于工作需要，重新系统回顾 Kubernetes 的编程。发现《Programming Kubernetes》这书写得比较系统。于是边学，边记录一些重点。

Controller

Controller Loop

配置例子

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apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: php-apache
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: php-apache
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

算法

desiredReplicas = ceil[currentReplicas * ( currentMetricValue / desiredMetricValue )]

currentMetricValue 为相关 pod 的 metric 平均数。

什么是同步原语

共享内存，多进程/线程的运行期设计模式已成主流的今天，你有好奇一下，进程/线程间的怎么同步的吗？大部分人知道，我们用的开发语言，或类库函数库，已经提供了看起来很漂亮的封装。然而在漂亮的面子工程后面，大部分归根到底是要内核或/和 CPU 硬件去完成这些同步的。而反过来，只要我们理解了内部原理，你就可以快速理解那些漂亮的面子工程，和他们可能的性能问题，进而选择一个适合你的“面子工程”。而这些内部原理，就是同步原语。

Istio Canary（金丝雀）上线

📅 2021年03月20日 · ☕ 1 分钟

按比例分配分配新旧版本流量

VirtualService:

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apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews
spec:
  hosts:
    - reviews
  http:
  - route:
    - destination:
        host: reviews
        subset: v1
      weight: 75
    - destination:
        host: reviews
        subset: v2
      weight: 25

DestinationRule :

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apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: bookinfo-ratings
spec:
  host: reviews
  trafficPolicy:
    loadBalancer:
      simple: LEAST_CONN
  subsets:
  - name: v1
    labels:
      version: v1
    trafficPolicy:
      loadBalancer:
        simple: ROUND_ROBIN
  - name: v2
    labels:
      version: v2
    trafficPolicy:
      loadBalancer:
        simple: ROUND_ROBIN

根据请求源 pod 的 label 路由

使用 sourceLabels 规则，可以根据源 pod 的 label 进行路由。这里用了 version 这个 label。即根据pod的应用版本进行路由。
这样的路由规则实际是使用于发起调用方的 sidecar。

程序员的平行宇宙 —— eBPF 系统级跟踪技术简单入门

📅 2021年03月10日 · ☕ 5 分钟

Linus Torvalds in 1991

程序员的平行宇宙

程序员有两个世界：

一个是编码世界，我们很容易认为，我们考虑了一切，也完成了一切的代码。
然后是运行世界，我们发现，无论我们多么的严谨和考虑一切，世界总是有异常。异常就好像电磁波，一开始，我们只能通过它引发的结果而发现它，而不能直接观察。因为它总出现在那些黑暗的角落，如果我们手中没有电简和电磁波示波器，一切只能依靠猜测和迷信。最后，我们进入了一个用猜测驱动的世界。有时候，我们运气好，猜中了。有时候，我们只能在 release 前多上香。

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.

系统级跟踪 eBPF 工具 —— bpftrace 入门

📅 2021年03月08日 · ☕ 1 分钟

bpftrace 简介

bpftrace 简单使用

查询可以跟踪的内核函数，以 sleep 为关键字

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$ bpftrace -l '*open*'

tracepoint:syscalls:sys_exit_open_tree
tracepoint:syscalls:sys_enter_open
...
kprobe:vfs_open
kprobe:tcp_try_fastopen
...

跟踪所有 sys_enter_open() 系统调用

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$ bpftrace -e 'tracepoint:syscalls:sys_enter_open{ printf("%s %s\n", comm,str(args->filename)); }' | grep vi

然后在另外一个终端中

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$ vi /etc/hosts

可以看到在 bpftrace 终端中输出：

Chat