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钉钉消息 html转图片总结

在golang 自行调度的场景下，wkhtmltoimage （wkhtmltopdf）这个工具遇到的一些问题

  1. 因为依赖qt 而qt 需要在主线程中创建application
WARNING: QApplication was not created in main() thread

这样造成的后果是 因为qt没有初始化好，后面转换出现了乱码

  1. cgo调用c代码的时候，如果go的调度器切换了线程，那么cgo有可能会失败
    cgo Interacting with C Library that uses Thread Local Storage
//https://github.com/bratsche/glib/blob/master/glib/gmain.c
/**
 * g_main_context_pop_thread_default:
 * @context: a #GMainContext object, or %NULL
 *
 * Pops @context off the thread-default context stack (verifying that
 * it was on the top of the stack).
 *
 * Since: 2.22
 **/
void
g_main_context_pop_thread_default (GMainContext *context)
{
  GQueue *stack;

  if (context == g_main_context_default ())
    context = NULL;

  stack = g_static_private_get (&thread_context_stack);

  g_return_if_fail (stack != NULL);
  g_return_if_fail (g_queue_peek_head (stack) == context);

  g_queue_pop_head (stack);

  g_main_context_release (context);
  if (context)
    g_main_context_unref (context);
}
(process:14437): GLib-CRITICAL **: 03:30:03.635: g_main_context_pop_thread_default: assertion 'stack != NULL' failed
fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x7fb271104041]

runtime stack:
runtime.throw(0x117aaed, 0x2a)
	/usr/local/go/src/runtime/panic.go:1116 +0x72
runtime.sigpanic()
	/usr/local/go/src/runtime/signal_unix.go:726 +0x4ac

goroutine 23316 [syscall]:
runtime.cgocall(0xef1610, 0xc0008c99e8, 0xc0008c99f0)
	/usr/local/go/src/runtime/cgocall.go:133 +0x5b fp=0xc0008c99b8 sp=0xc0008c9980 pc=0x4058bb
github.com/shezadkhan137/go-wkhtmltoimage._Cfunc_wkhtmltoimage_deinit(0x0)
	_cgo_gotypes.go:143 +0x49 fp=0xc0008c99e8 sp=0xc0008c99b8 pc=0xd779a9
github.com/shezadkhan137/go-wkhtmltoimage.Destroy()

最终的解决办法是用

runtime.LockOSThread()
runtime.UnlockOSThread()
通过不让调度器切换线程来避免这样的问题，这样的操作当然是有代价的 性能会下降

中台定时任务故障排查跟踪

golang 调度研究

hell hello heh 
os层 最大线程数量
https://stackoverflow.com/questions/344203/maximum-number-of-threads-per-process-in-linux


golang 最大线程数量 10000 
可以通过 runtime debug 包中的SetMaxThreads() 来设置  

创建的条件是，
当前的thread 如果被block 了 （比如在io等待）将会重新创建一个新的os层的thread 来继续工作
It will create a new thread once current one is blocked.

golang实现接口注意事项

简介

golang实现接口有很多需要注意的地方

var dataSlice []int = foo()
var interfaceSlice []interface{} = dataSlice

Why can't I assign any slice to an []interface{}

原因：
[]interface{} is not an interface!
长度不一样 []interface{} 占两个words 一个是类型，一个是内容或者指针 对于N长的数据总长是 N*2

如果非要用 可以这样

var dataSlice []int = foo()
var interfaceSlice []interface{} = make([]interface{}, len(dataSlice)) //这里指定已知类型的长度
for i, d := range dataSlice {
	interfaceSlice[i] = d
}

参考资料

golang 引入私有repo

参考资料

go env -w GOPRIVATE=github.com/woshidama323/FILECOIN

来源

注意：

加私有仓储 需要提供当前环境的 ssh public key到github私有仓储中

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