erlang httpc：请求同步块？

Question

httpc_request(Url) ->
    HttpOpts = [{timeout, 5000}],
    Opts = [{sync, true}, {full_result, false}, {body_format, binary}],   
    httpc:request(get, {Url, []}, HttpOpts, Opts).

在gen_server进程p（pid = P）中，执行函数httpc_request（url），我发现某个进程可能在httpc中阻塞：handle_answer receive

process_info(P, current_function)显示结果：

{current_function,{httpc,handle_answer,3}}

ets:match_object(httpc_manager__handler_db, {_='_', _='_', P})显示结果：

[{Ref,HandlePid,P}]

process_info(HandlePid, [current_function, status])显示结果：

[{current_function,{gen_server,loop,6}},{status,waiting}]

进程P是使用receive等待HandlePid回复，但是HandlePid在gen_server循环中等待接收tcp包，如何解决这个问题？