#0  0x00007ffff74ef100 in __write_nocancel ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007ffff772015d in apr_socket_send () from /usr/lib/libapr-1.so.0
#2  0x0000000000442278 in emulate_sendfile (c=0x7ffff7f01a20, fd=0x7ffff7eeb3e8, 
    hdtr=0x7fffffffdcc0, offset=0, length=9927, nbytes=0x7fffffffdcf8)
    at core_filters.c:493
#3  0x0000000000442ffc in ap_core_output_filter (f=0x7ffff7f01a68, b=0x7ffff7e850a0)
    at core_filters.c:857
#4  0x00000000004519c2 in ap_pass_brigade (next=0x7ffff7f01a68, bb=0x7ffff7eeb548)
    at util_filter.c:526
#5  0x000000000046ab37 in ap_http_outerror_filter (f=0x7ffff7efa5e8, b=0x7ffff7eeb548)
    at http_filters.c:1664
#6  0x00000000004519c2 in ap_pass_brigade (next=0x7ffff7efa5e8, bb=0x7ffff7eeb548)
    at util_filter.c:526
#7  0x000000000046a369 in ap_http_header_filter (f=0x7ffff7efa5c0, b=0x7ffff7eeb548)
    at http_filters.c:1327
#8  0x00000000004519c2 in ap_pass_brigade (next=0x7ffff7efa5c0, bb=0x7ffff7eeb548)
    at util_filter.c:526
#9  0x0000000000433743 in ap_content_length_filter (f=0x7ffff7efa598, b=0x7ffff7eeb548)
    at protocol.c:1349
#10 0x00000000004519c2 in ap_pass_brigade (next=0x7ffff7efa598, bb=0x7ffff7eeb548)
    at util_filter.c:526
#11 0x000000000046b7a5 in ap_byterange_filter (f=0x7ffff7efa570, bb=0x7ffff7eeb548)
    at byterange_filter.c:262
#12 0x00000000004519c2 in ap_pass_brigade (next=0x7ffff7efa570, bb=0x7ffff7eeb548)
---Type <return> to continue, or q <return> to quit---
    at util_filter.c:526
#13 0x000000000043bd39 in default_handler (r=0x7ffff7ef90a0) at core.c:3815
#14 0x0000000000443b7a in ap_run_handler (r=0x7ffff7ef90a0) at config.c:158
#15 0x000000000044446b in ap_invoke_handler (r=0x7ffff7ef90a0) at config.c:376
#16 0x00000000004667c7 in ap_process_request (r=0x7ffff7ef90a0) at http_request.c:282
#17 0x00000000004636d8 in ap_process_http_connection (c=0x7ffff7f01290)
    at http_core.c:190
#18 0x000000000044d339 in ap_run_process_connection (c=0x7ffff7f01290)
    at connection.c:43
#19 0x000000000044d7ce in ap_process_connection (c=0x7ffff7f01290, csd=0x7ffff7f010a0)
    at connection.c:190
#20 0x000000000048c9cd in child_main (child_num_arg=0) at prefork.c:667
#21 0x000000000048cac5 in make_child (s=0x7ffff7fec1a0, slot=0) at prefork.c:712
#22 0x000000000048d07d in ap_mpm_run (_pconf=0x7ffff7ff1028, plog=0x7ffff7fa8028, 
    s=0x7ffff7fec1a0) at prefork.c:988
#23 0x0000000000429bd5 in main (argc=2, argv=0x7fffffffe6f8) at main.c:739