CURL_LOCK_DATA_DNS threaded-shared-conn.c hangs

[Fricker95]

I did this

In threaded-shared-conn.c from the examples, i added CURL_LOCK_DATA_DNS to the curl share handle and the program hangs. I have tried to compile curl with --disable-threaded-resolver and --enable-threaded-resolver both causes the same outcome.

output

Thread 0, gets http://www.example.com

Thread 1, gets http://www.example.com

• Found bundle for host www.example.com: 0x7fa91e0045b0 [serially]
• Server doesn't support multiplex (yet)
• Hostname 'www.example.com' was found in DNS cache
• Trying 93.184.216.34:80...
• Trying 93.184.216.34:80...
• Connected to www.example.com (93.184.216.34) port 80 (docs/libcurl/libcurl.m4 bug #1)
• Connected to www.example.com (93.184.216.34) port 80 (#0)

GET / HTTP/1.1
Host: www.example.com
Accept: /

GET / HTTP/1.1
Host: www.example.com
Accept: /

• Mark bundle as not supporting multiuse
  < HTTP/1.1 200 OK
  < Accept-Ranges: bytes
  < Age: 474184
  < Cache-Control: max-age=604800
  < Content-Type: text/html; charset=UTF-8
  < Date: Mon, 18 May 2020 04:51:51 GMT
  < Etag: "3147526947+gzip"
  < Expires: Mon, 25 May 2020 04:51:51 GMT
  < Last-Modified: Thu, 17 Oct 2019 07:18:26 GMT
  < Server: ECS (sjc/4E74)
  < Vary: Accept-Encoding
  < X-Cache: HIT
  < Content-Length: 1256
  <
• Mark bundle as not supporting multiuse
  < HTTP/1.1 200 OK
  < Accept-Ranges: bytes
  < Age: 348481
  < Cache-Control: max-age=604800
  < Content-Type: text/html; charset=UTF-8
  < Date: Mon, 18 May 2020 04:51:51 GMT
  < Etag: "3147526947+gzip"
  < Expires: Mon, 25 May 2020 04:51:51 GMT
  < Last-Modified: Thu, 17 Oct 2019 07:18:26 GMT
  < Server: ECS (sjc/4E44)
  < Vary: Accept-Encoding
  < X-Cache: HIT
  < Content-Length: 1256
  <

curl/libcurl version

Occurs in both 7.70.0 & 7.69.0:

• curl 7.69.0 (x86_64-apple-darwin19.3.0) libcurl/7.69.0 SecureTransport zlib/1.2.11 libidn2/2.3.0 nghttp2/1.40.0
  Release-Date: 2020-03-04
  Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
  Features: AsynchDNS HTTP2 IDN IPv6 Largefile libz NTLM NTLM_WB SSL UnixSockets

• curl 7.70.0 (x86_64-apple-darwin19.4.0) libcurl/7.70.0 openssl/1.1.1d zlib/1.2.11 nghttp2/1.40.0
  Release-Date: 2020-04-29
  Protocols: DICT FILE FTP FTPS GOPHER HTTP HTTPS IMAP IMAPS POP3 POP3S RTSP SMB SMBS SMTP SMTPS TELNET TFTP
  Features: SSL IPv6 UnixSockets libz NTLM NTLM_WB TLS-SRP HTTP2 HTTPS-proxy ( w/ & w/o AsynchDNS)

operating system

Darwin 19.4.0 Darwin Kernel Version 19.4.0: Wed Mar 4 22:28:40 PST 2020; root:xnu-6153.101.6~15/RELEASE_X86_64 x86_64

[bagder]

"Added" means that you also share connection cache, right? That one is already a known bug: #4915 ...

[Fricker95]

Yes, ok thank you! Should I close this issue?

[bagder]

If the problem goes away when you don't share the connection cache anymore, then yes this is then a duplicate.