title: strace on Linux not logging all calls to open()
body: <p>I am using strace to capture calls to open(), close() and read() on Linux. The target process is the jetty web server. As far as I can tell, strace is not logging all calls to open(). Maybe the others too, I have not tried to correlate the file descriptors to open() calls.</p>
  
  <p>For example, starting strace:</p>
  
  <p>strace -f -e trace=open,close,read -o/tmp/strace.out -p62881</p>
  
  <p>I then use wget to fetch 100 static files; all were retrieved successfully. In one run, only 56 open events were logged; on another run of 100 different files, I got 66 open events.</p>
  
  <p>I believe that using "-f" results in strace attaching to all the LWPIDs for the threads ("Process 62881 attached with 25 threads - interrupt to quit
  "); when I try to explicitly attach to all using multiple "-p" options, I get a single "attach" success message, but multiple "Operation not permitted messages", one for each child PID.</p>
  
  <p>I restarted Jetty to clear its cache before my tests.</p>
  
  <p>Kernel version is 2.6.32-504.3.3.el6.x86_64 (Red Hat). Strace package version is strace-4.5.19-1.19.el6.x86_64.</p>
  
  <p>What am I missing?</p>
  
  <p>Thanks</p>