VSCode Golang dlv调试数据截断问题及处理方法

使用VSCode对Golang程序进行调试时会遇到数据截断问题，string只显示前64个字符，array只显示前64个数据。经查dlv是支持以参数方式来控制的。

发现VSCode的Golang插件里面有个叫做go.delveConfig的配置，是可以设置dlv参数的。分享一下我的整个Golang配置：

"go.buildOnSave": "off",
  "go.formatTool": "goimports",
  "go.lintTool": "golangci-lint", //go get -u github.com/golangci/golangci-lint/cmd/golangci-lint
  "go.autocompleteUnimportedPackages": true,
  "go.gotoSymbol.includeImports": true,
  "go.useLanguageServer": true,
  "go.delveConfig": {
    "dlvLoadConfig": {
      "followPointers": true,
      "maxVariableRecurse": 3,
      "maxStringLen": 1024,
      "maxArrayValues": 1024,
      "maxStructFields": -1
    },
  },
  "[go]": {
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
      "source.organizeImports": true
    }
  },

需要改的主要是maxStringLen、maxArrayValues、maxVariableRecurse这三个字段。

参考：https://stackoverflow.com/questions/52416263/how-do-i-print-the-full-value-of-a-string-variable-in-delve

ps：下面看下Golang dlv 工具debug 调试注意项

总结一下关于Go 的调试工具dlv：https://github.com/derekparker/delve 的使用注意项。

安装：

go get -u github.com/go-delve/delve/cmd/dlv

配置：

以Centos为例

export GOROOT=/usr/lib/golang
export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin

使用

以某go服务为例：

• dlv debug xxx.go 指定需要debug的文件
• 进入dlv交互式窗口后，b <filename>:<line> 指定断点
• r arg 指定运行参数
• n 执行一行
• c 运行至断点或程序结束

dlv debug /home/xxx/server.go
(dlv) b /home/xxx/server.go:258
(dlv) r 1
(dlv) n
(dlv) c

注意： b <filename>:<line> 指定断点时，若该行号对应的代码内容为无具体语义的代码（括号、注释等），则会报错：

Command failed: could not find /home/xxx/server.go:258

此时可用list 命令先查看上下文代码，避免将无具体语义的代码设为断点。

命令集

The following commands are available:
    args ------------------------ Print function arguments.
    break (alias: b) ------------ Sets a breakpoint.
    breakpoints (alias: bp) ----- Print out info for active breakpoints.
    call ------------------------ Resumes process, injecting a function call (EXPERIMENTAL!!!)
    clear ----------------------- Deletes breakpoint.
    clearall -------------------- Deletes multiple breakpoints.
    condition (alias: cond) ----- Set breakpoint condition.
    config ---------------------- Changes configuration parameters.
    continue (alias: c) --------- Run until breakpoint or program termination.
    deferred -------------------- Executes command in the context of a deferred call.
    disassemble (alias: disass) - Disassembler.
    down ------------------------ Move the current frame down.
    edit (alias: ed) ------------ Open where you are in $DELVE_EDITOR or $EDITOR
    exit (alias: quit | q) ------ Exit the debugger.
    frame ----------------------- Set the current frame, or execute command on a different frame.
    funcs ----------------------- Print list of functions.
    goroutine ------------------- Shows or changes current goroutine
    goroutines ------------------ List program goroutines.
    help (alias: h) ------------- Prints the help message.
    list (alias: ls | l) -------- Show source code.
    locals ---------------------- Print local variables.
    next (alias: n) ------------- Step over to next source line.
    on -------------------------- Executes a command when a breakpoint is hit.
    print (alias: p) ------------ Evaluate an expression.
    regs ------------------------ Print contents of CPU registers.
    restart (alias: r) ---------- Restart process.
    set ------------------------- Changes the value of a variable.
    source ---------------------- Executes a file containing a list of delve commands
    sources --------------------- Print list of source files.
    stack (alias: bt) ----------- Print stack trace.
    step (alias: s) ------------- Single step through program.
    step-instruction (alias: si)  Single step a single cpu instruction.
    stepout --------------------- Step out of the current function.
    thread (alias: tr) ---------- Switch to the specified thread.
    threads --------------------- Print out info for every traced thread.
    trace (alias: t) ------------ Set tracepoint.
    types ----------------------- Print list of types
    up -------------------------- Move the current frame up.
    vars ------------------------ Print package variables.
    whatis ---------------------- Prints type of an expression.

总结