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开发人员定位代码中的问题时，通常会借助 Print语句（如fmt.Println） 来打印变量的值，进而推断程序执行结果是否符合预期。在某些更复杂的场景下，打印语句可能难以胜任，调试器会更好地协助我们定位问题。
调试器可以帮助我们控制tracee（被调试进程、线程）的执行，也可以观察tracee的运行时内存、寄存器状态，借此我们可以实现代码的逐语句执行、控制代码执行流程、检查变量值是否符合预期，等等
调试器要支持的重要操作，通常包括：
- 设置断点，在指定内存地址、函数、语句、文件行号处设置断点；
- 单步执行，单步执行一条指令，单步执行一条语句，或运行到下个断点处；
- 获取、设置寄存器信息；
- 获取、设置内存信息；
- 对表达式进行估值计算；
- 调用函数；
- 其他；
- GDB 最早期的调试工具，现在用的很少。对goroutine场景支持不足，不能很好的应对goroutine的调试
- LLDB macOS 系统推荐的标准调试工具，但 Go 的一些专有特性支持的比较少。
- Delve 专门为 Go 语言打造的调试工具，使用最为广泛。
DWARF：是一种调试信息标准，指导编译器将调试信息生成到目标文件中，指导链接器合并存储在多个目标文件中的调试信息，调试器将加载此调试信息。简言之，DWARF用来协调编译器、链接器和调试器之间的工作
调试器可以分为两种类型：指令级调试器和符号级调试器
指令级调试器，其操作的对象是机器指令。通过处理器指令patch技术就可以实现指令级调试，不需要调试符号信息。 它仅适用于指令或汇编语言级别的操作，不支持源代码级别的操作。
符号级调试器，其操作的对象不仅是机器指令，更重要的是支持源代码级的操作。它可以提取和解析调试符号信息，建立内存地址、指令地址和源代码之间的映射关系，支持在源代码语句上设置断点的时候，将其转换为精确的机器指令断点，也支持其他方便的操作
# Version: 1.22.1
➜ ~ dlv --help
Delve is a source level debugger for Go programs.
Delve enables you to interact with your program by controlling the execution of the process,
evaluating variables, and providing information of thread / goroutine state, CPU register state and more.
The goal of this tool is to provide a simple yet powerful interface for debugging Go programs.
Pass flags to the program you are debugging using `--`, for example:
`dlv exec ./hello -- server --config conf/config.toml`
Usage:
dlv [command]
Available Commands:
attach Attach to running process and begin debugging.
completion Generate the autocompletion script for the specified shell
connect Connect to a headless debug server with a terminal client.
core Examine a core dump.
dap Starts a headless TCP server communicating via Debug Adaptor Protocol (DAP).
debug Compile and begin debugging main package in current directory, or the package specified.
exec Execute a precompiled binary, and begin a debug session.
help Help about any command
test Compile test binary and begin debugging program.
trace Compile and begin tracing program.
version Prints version.
Additional help topics:
dlv backend Help about the --backend flag.
dlv log Help about logging flags.
dlv redirect Help about file redirection.| 命令 | 解释 |
|---|---|
| attach | 这个命令将使Delve控制一个已经运行的进程，并开始一个新的调试会话。 当退出调试会话时，你可以选择让该进程继续运行或杀死它。 |
| debug | 默认情况下，没有参数，Delve将编译当前目录下的 "main "包，并开始调试。或者，你可以指定一个包的名字，Delve将编译该包，并开始一个新的调试会话 |
进入 dlv 调试后的指令
✗ dlv debug
Type 'help' for list of commands.
(dlv) help
The following commands are available:
Running the program:
call ------------------------ Resumes process, injecting a function call (EXPERIMENTAL!!!)
continue (alias: c) --------- Run until breakpoint or program termination.
next (alias: n) ------------- Step over to next source line.
rebuild --------------------- Rebuild the target executable and restarts it. It does not work if the executable was not built by delve.
restart (alias: r) ---------- Restart process.
step (alias: s) ------------- Single step through program.
step-instruction (alias: si) Single step a single cpu instruction.
stepout (alias: so) --------- Step out of the current function.
Manipulating breakpoints:
break (alias: b) ------- Sets a breakpoint.
breakpoints (alias: bp) Print out info for active breakpoints.
clear ------------------ Deletes breakpoint.
clearall --------------- Deletes multiple breakpoints.
condition (alias: cond) Set breakpoint condition.
on --------------------- Executes a command when a breakpoint is hit.
toggle ----------------- Toggles on or off a breakpoint.
trace (alias: t) ------- Set tracepoint.
watch ------------------ Set watchpoint.
Viewing program variables and memory:
args ----------------- Print function arguments.
display -------------- Print value of an expression every time the program stops.
examinemem (alias: x) Examine raw memory at the given address.
locals --------------- Print local variables.
print (alias: p) ----- Evaluate an expression.
regs ----------------- Print contents of CPU registers.
set ------------------ Changes the value of a variable.
vars ----------------- Print package variables.
whatis --------------- Prints type of an expression.
Listing and switching between threads and goroutines:
goroutine (alias: gr) -- Shows or changes current goroutine
goroutines (alias: grs) List program goroutines.
thread (alias: tr) ----- Switch to the specified thread.
threads ---------------- Print out info for every traced thread.
Viewing the call stack and selecting frames:
deferred --------- Executes command in the context of a deferred call.
down ------------- Move the current frame down.
frame ------------ Set the current frame, or execute command on a different frame.
stack (alias: bt) Print stack trace.
up --------------- Move the current frame up.
Other commands:
config --------------------- Changes configuration parameters.
disassemble (alias: disass) Disassembler.
dump ----------------------- Creates a core dump from the current process state
edit (alias: ed) ----------- Open where you are in $DELVE_EDITOR or $EDITOR
exit (alias: quit | q) ----- Exit the debugger.
funcs ---------------------- Print list of functions.
help (alias: h) ------------ Prints the help message.
libraries ------------------ List loaded dynamic libraries
list (alias: ls | l) ------- Show source code.
packages ------------------- Print list of packages.
source --------------------- Executes a file containing a list of delve commands
sources -------------------- Print list of source files.
target --------------------- Manages child process debugging.
transcript ----------------- Appends command output to a file.
types ---------------------- Print list of types
Type help followed by a command for full documentation.