Thread leak due to default (infinite) connection timeouts

[bgooren]

On a restart of one of our services that uses this client we observed some stuck threads. A thread dump revealed that several threads are stuck in the HTTP connection the prismic API:

"http-nio-9000-exec-3" #65 daemon prio=5 os_prio=0 cpu=124345.40ms elapsed=615154.36s tid=0x00007ff0aceb1800 nid=0x2bc9 runnable  [0x00007ff00c6d6000]
   java.lang.Thread.State: RUNNABLE
	at java.net.SocketInputStream.socketRead0(java.base@11.0.9.1/Native Method)
	at java.net.SocketInputStream.socketRead(java.base@11.0.9.1/SocketInputStream.java:115)
	at java.net.SocketInputStream.read(java.base@11.0.9.1/SocketInputStream.java:168)
	at java.net.SocketInputStream.read(java.base@11.0.9.1/SocketInputStream.java:140)
	at sun.security.ssl.SSLSocketInputRecord.read(java.base@11.0.9.1/SSLSocketInputRecord.java:476)
	at sun.security.ssl.SSLSocketInputRecord.readFully(java.base@11.0.9.1/SSLSocketInputRecord.java:459)
	at sun.security.ssl.SSLSocketInputRecord.decodeInputRecord(java.base@11.0.9.1/SSLSocketInputRecord.java:243)
	at sun.security.ssl.SSLSocketInputRecord.decode(java.base@11.0.9.1/SSLSocketInputRecord.java:181)
	at sun.security.ssl.SSLTransport.decode(java.base@11.0.9.1/SSLTransport.java:110)
	at sun.security.ssl.SSLSocketImpl.decode(java.base@11.0.9.1/SSLSocketImpl.java:1411)
	at sun.security.ssl.SSLSocketImpl.readApplicationRecord(java.base@11.0.9.1/SSLSocketImpl.java:1376)
	at sun.security.ssl.SSLSocketImpl$AppInputStream.read(java.base@11.0.9.1/SSLSocketImpl.java:963)
	at java.io.BufferedInputStream.fill(java.base@11.0.9.1/BufferedInputStream.java:252)
	at java.io.BufferedInputStream.read1(java.base@11.0.9.1/BufferedInputStream.java:292)
	at java.io.BufferedInputStream.read(java.base@11.0.9.1/BufferedInputStream.java:351)
	- locked <0x00000000d572b678> (a java.io.BufferedInputStream)
	at sun.net.www.http.HttpClient.parseHTTPHeader(java.base@11.0.9.1/HttpClient.java:754)
	at sun.net.www.http.HttpClient.parseHTTP(java.base@11.0.9.1/HttpClient.java:689)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(java.base@11.0.9.1/HttpURLConnection.java:1615)
	- locked <0x00000000d572b6d0> (a sun.net.www.protocol.https.DelegateHttpsURLConnection)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(java.base@11.0.9.1/HttpURLConnection.java:1520)
	- locked <0x00000000d572b6d0> (a sun.net.www.protocol.https.DelegateHttpsURLConnection)
	at java.net.URLConnection.getContent(java.base@11.0.9.1/URLConnection.java:749)
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getContent(java.base@11.0.9.1/HttpsURLConnectionImpl.java:430)
	at io.prismic.core.HttpClient.fetch(HttpClient.java:41)
	at io.prismic.Form$SearchForm.submit(Form.java:411)

This is happening because io.prismic.core.HttpClient#fetch uses a HttpURLConnection without specifying any timeouts. By default the underlying URLConnection has a connectTimeout and readTimeout of 0 - which means infinite.

I think this client is not maintained anymore, given the lack of updates.
This ticket serves as a warning/documentation for others.

The current code doesn't provide any methods/hooks to fix this, besides forking the code & fixing it yourself.