What does the 'cannot find package' error mean during go build?

Goprovidesbuilt-insupportforhandlingenvironmentvariablesviatheospackage,enablingdeveloperstoread,set,andmanageenvironmentdatasecurelyandefficiently.Toreadavariable,useos.Getenv("KEY"),whichreturnsanemptystringifthekeyisnotset,orcombineos.Lo

Run the child process using the os/exec package, create the command through exec.Command but not execute it immediately; 2. Run the command with .Output() and catch stdout. If the exit code is non-zero, return exec.ExitError; 3. Use .Start() to start the process without blocking, combine with .StdoutPipe() to stream output in real time; 4. Enter data into the process through .StdinPipe(), and after writing, you need to close the pipeline and call .Wait() to wait for the end; 5. Exec.ExitError must be processed to get the exit code and stderr of the failed command to avoid zombie processes.

FornewGo1.21 projects,useslogforofficialstructuredloggingsupport;2.Forhigh-performanceproductionservices,chooseZaporZerologduetotheirspeedandlowallocations;3.ForeaseofuseandrichintegrationslikeSlackorSentryhooks,Logrusisidealdespitelowerperformance;4

UseURLpathversioninglike/api/v1forclear,routable,anddeveloper-friendlyversioning.2.Applysemanticversioningwithmajorversions(v1,v2)only,avoidingmicro-versionslikev1.1topreventroutingcomplexity.3.OptionallysupportcontentnegotiationviaAcceptheadersifalr

Use Go generics and container/list to achieve thread-safe LRU cache; 2. The core components include maps, bidirectional linked lists and mutex locks; 3. Get and Add operations ensure concurrency security through locks, with a time complexity of O(1); 4. When the cache is full, the longest unused entry will be automatically eliminated; 5. In the example, the cache with capacity of 3 successfully eliminated the longest unused "b". This implementation fully supports generic, efficient and scalable.

In Go, creating and using custom error types can improve the expressiveness and debugability of error handling. The answer is to create a custom error by defining a structure that implements the Error() method. For example, ValidationError contains Field and Message fields and returns formatted error information. The error can then be returned in the function, detecting specific error types through type assertions or errors.As to execute different logic. You can also add behavioral methods such as IsCritical to custom errors, which are suitable for scenarios that require structured data, differentiated processing, library export or API integration. In simple cases, errors.New, and predefined errors such as ErrNotFound can be used for comparable

The correct way to process signals in Go applications is to use the os/signal package to monitor the signal and perform elegant shutdown. 1. Use signal.Notify to send SIGINT, SIGTERM and other signals to the channel; 2. Run the main service in goroutine and block the waiting signal; 3. After receiving the signal, perform elegant shutdown with timeout through context.WithTimeout; 4. Clean up resources such as closing database connections and stopping background goroutine; 5. Use signal.Reset to restore the default signal behavior when necessary to ensure that the program can be reliably terminated in Kubernetes and other environments.

Using structured logging, adding context, controlling log levels, avoiding logging sensitive data, using consistent field names, correctly logging errors, taking into account performance, centrally monitoring logs and unifying configurations are best practices in Go to achieve efficient logging. First, structured logs in JSON format (such as using uber-go/zap or rs/zerolog) facilitate machine parsing and integrating ELK, Datadog and other tools; second, log traceability is enhanced by requesting context information such as ID and user ID, and can be injected through context.Context or HTTP middleware; third, use Debug, Info, Warn, Error levels reasonably, and operate through environment variables.