凯末尔的缓慢异常报告答案

【问题标题】：Slow exception report in Kemal凯末尔的缓慢异常报告
【发布时间】：2020-02-07 18:01:59
【问题描述】：

我使用水晶 32.1 和凯末尔。如果我有运行时异常，打印回溯需要 21 秒。知道为什么需要这么长时间吗？

500 GET /chats/by_sale/1 21280.52ms

回溯：

web_1     | I, [2020-02-07 17:57:33 +00:00 #1]  INFO -- : [1]
web_1     | Exception: Expected string for object name (JSON::Error)
web_1     |   from /usr/share/crystal/src/json/builder.cr:308:16 in 'start_scalar'
web_1     |   from /usr/share/crystal/src/json/builder.cr:295:11 in 'start_scalar'
web_1     |   from /usr/share/crystal/src/json/builder.cr:194:5 in 'start_object'
web_1     |   from src/service/json.cr:220:5 in 'object'
web_1     |   from src/controller/chat.cr:37:5 in '->'
web_1     |   from lib/kemal/src/kemal/route.cr:255:3 in '->'
web_1     |   from lib/kemal/src/kemal/route_handler.cr:255:3 in 'process_request'
web_1     |   from lib/kemal/src/kemal/route_handler.cr:17:7 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/websocket_handler.cr:13:14 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/filter_handler.cr:21:7 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from src/middleware/authenticate.cr:17:7 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/static_file_handler.cr:68:9 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/exception_handler.cr:8:7 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/log_handler.cr:8:37 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/handler.cr:26:7 in 'call_next'
web_1     |   from lib/kemal/src/kemal/init_handler.cr:12:7 in 'call'
web_1     |   from /usr/share/crystal/src/http/server/request_processor.cr:48:11 in 'process'
web_1     |   from /usr/share/crystal/src/http/server/request_processor.cr:22:3 in 'process'
web_1     |   from /usr/share/crystal/src/http/server.cr:497:5 in 'handle_client'
web_1     |   from /usr/share/crystal/src/http/server.cr:463:13 in '->'
web_1     |   from /usr/share/crystal/src/fiber.cr:255:3 in 'run'
web_1     |   from /usr/share/crystal/src/fiber.cr:47:34 in '->'
web_1     |   from ???
web_1     |
web_1     | 2020-02-07 17:57:54 UTC 500 GET /chats/by_sale/1 21280.52ms

【问题讨论】：

标签： crystal-lang kemal

【解决方案1】：

评论很大，所以让它成为一个答案。

我将如何处理这个问题是通过在 gdb 中运行您的服务器，然后在“21 秒暂停中间”您在服务器中按 ctrl+c。它会让你进入 gdb。然后运行 gdb backtrace 命令，看看它是否告诉你什么。另一种选择可能是在其上运行分析器，其中提到了一些 here: 甚至 gdb "poor man's profiler"，它也适用于水晶（在 OS X 中，sample 命令执行类似 FWIW 的操作），并在相关减速期间运行它。

【讨论】：