CollecTor's relaydescs module freezes while downloading from directory authorities

This morning, 2017-06-14 ~07:00, I noticed that the latest consensus retrieved by CollecTor was valid after 2017-06-13 17:00.

The last log lines from the relaydescs module were:

2017-06-13 17:05:00,001 INFO o.t.c.c.CollecTorMain:66 Starting relaydescs module of CollecTor.
2017-06-13 17:05:26,184 INFO o.t.c.r.CachedRelayDescriptorReader:255 Finished importing relay descriptors from local Tor data directories:
cached-consensus: 2017-06-13 17:00:00
cached-descriptors: parsed 0, skipped 24560 server descriptors
cached-descriptors.new: parsed 608, skipped 8585 server descriptors
cached-extrainfo: parsed 0, skipped 24543 extra-info descriptors
cached-extrainfo.new: parsed 607, skipped 8239 extra-info descriptors
v3-status-votes: parsed 8, skipped 0 votes

All other modules continued as usual.

Here's a stack trace obtained using jcmd:

"CollecTor-Scheduled-Thread-8" daemon prio=10 tid=0x00007fedd8006800 nid=0x6411 runnable [0x00007fee023fd000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:153)
        at java.net.SocketInputStream.read(SocketInputStream.java:122)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
        at java.io.BufferedInputStream.read1(BufferedInputStream.java:275)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:334)
        - locked <0x000000078fd3b3d8> (a java.io.BufferedInputStream)
        at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:707)
        at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:650)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1371)
        - locked <0x000000078fd3b418> (a sun.net.www.protocol.http.HttpURLConnection)
        at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:468)
        at org.torproject.collector.relaydescs.RelayDescriptorDownloader.downloadResourceFromAuthority(RelayDescriptorDownloader.java:869)
        at org.torproject.collector.relaydescs.RelayDescriptorDownloader.downloadDescriptors(RelayDescriptorDownloader.java:817)
        at org.torproject.collector.relaydescs.ArchiveWriter.startProcessing(ArchiveWriter.java:176)
        at org.torproject.collector.cron.CollecTorMain.run(CollecTorMain.java:67)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:473)
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)

I stopped and restarted CollecTor and am now working on filling the gap of relay descriptors published in these ~16 hours by syncing from the backup instance.

I guess the fix is to start using a timeout somewhere. It's just curious that we didn't run into this case before. We didn't change anything there recently, did we?