Hi,
some time I ago, I had a problem, when opening many http connections in
multiple threads.
(http://www.mail-archive.com/synalist-public@lists.sourceforge.net/msg02955.html)
I never followed up on it, because I moved, and it does not happen in my
apartment.
But now is christmas, I'm visiting my mother, and the problem is there
again...
However, I figured out, why it does not work.
It has nothing to do with http or multithreading, but with the DNS requests.
Synapse sends the query correctly to the router (192.168.1.100), but
there never comes a response!
See: (the problem is with was.duesseldorf.de and
ausleihe.staatsbibliothek-berlin.de)
317 55.626416000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x8c97 A was.duesseldorf.de
318 55.631498000 192.168.1.2 192.168.1.100
DNS 92 Standard query 0xb7d8 A katalog.bibl.fh-duesseldorf.de
319 55.631908000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x9adb A was.duesseldorf.de
320 55.631995000 192.168.1.2 192.168.1.100
DNS 85 Standard query 0x8bd8 A kataloge.uni-hamburg.de
321 55.632421000 192.168.1.100 192.168.1.2
DNS 108 Standard query response 0xb7d8 A 195.37.241.41
322 55.632847000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0x6c9f A opac.hu-berlin.de
324 55.633813000 192.168.1.2 192.168.1.100
DNS 77 Standard query 0xa562 A ssl.muenchen.de
325 55.634324000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0x704c A ausleihe.staatsbibliothek-berlin.de
326 55.634536000 192.168.1.2 192.168.1.100
DNS 91 Standard query 0xe40e A katalog.ub.uni-duesseldorf.de
327 55.634648000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0xf645 A ausleihe.staatsbibliothek-berlin.de
328 55.635461000 192.168.1.2 192.168.1.100
DNS 91 Standard query 0x627a A katalog.ub.uni-duesseldorf.de
329 55.635520000 192.168.1.2 192.168.1.100
DNS 95 Standard query 0xcacf A webopac.stadtbibliothek-aachen.de
330 55.635685000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x877a A was.duesseldorf.de
331 55.635772000 192.168.1.2 192.168.1.100
DNS 86 Standard query 0x9164 A sisis.bth.rwth-aachen.de
332 55.635791000 192.168.1.2 192.168.1.100
DNS 87 Standard query 0xecd6 A aleph-www.ub.fu-berlin.de
333 55.642489000 192.168.1.100 192.168.1.2
DNS 107 Standard query response 0xe40e A 134.99.136.36
335 55.645576000 192.168.1.100 192.168.1.2
DNS 107 Standard query response 0x627a A 134.99.136.36
337 55.650951000 192.168.1.100 192.168.1.2
DNS 103 Standard query response 0xecd6 A 160.45.152.64
346 55.713099000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0x877a A 194.113.247.117
347 55.713213000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x1256 AAAA was.duesseldorf.de
348 55.719893000 192.168.1.100 192.168.1.2
DNS 128 Standard query response 0x8bd8 CNAME
kataloge.rrz.uni-hamburg.de A 134.100.53.84
349 55.720015000 192.168.1.2 192.168.1.100
DNS 89 Standard query 0x16a5 A kataloge.rrz.uni-hamburg.de
350 55.727284000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0x6c9f CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
351 55.727362000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0x055e A aleph.ub.hu-berlin.de
352 55.735932000 192.168.1.100 192.168.1.2
DNS 114 Standard query response 0xa562 CNAME hermes.muenchen.de
A 194.113.40.200
353 55.736012000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0xd5f5 A hermes.muenchen.de
354 55.751908000 192.168.1.100 192.168.1.2
DNS 113 Standard query response 0xf645 A 194.94.133.71
355 55.751987000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0xc723 AAAA
ausleihe.staatsbibliothek-berlin.de
365 55.791741000 192.168.1.100 192.168.1.2
DNS 111 Standard query response 0xcacf A 91.102.137.88
367 55.831062000 192.168.1.100 192.168.1.2
DNS 121 Standard query response 0x9164 CNAME
opac.bth.rwth-aachen.de A 134.130.184.19
368 55.831140000 192.168.1.2 192.168.1.100
DNS 85 Standard query 0xdede A opac.bth.rwth-aachen.de
369 55.862966000 192.168.1.100 192.168.1.2
DNS 137 Standard query response 0x1256
370 55.863055000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0xfa79 A was.duesseldorf.de
371 55.863849000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0xfa79 A 194.113.247.117
374 55.864058000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0xcccd A was.duesseldorf.de
375 55.864762000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0xcccd A 194.113.247.117
377 55.881045000 192.168.1.100 192.168.1.2
DNS 105 Standard query response 0x16a5 A 134.100.53.84
382 55.897991000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0x055e A 141.20.84.140
384 55.906141000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0xd5f5 A 194.113.40.200
390 55.929929000 192.168.1.100 192.168.1.2
DNS 162 Standard query response 0xc723
391 55.929998000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0x7685 A ausleihe.staatsbibliothek-berlin.de
392 55.930828000 192.168.1.100 192.168.1.2
DNS 113 Standard query response 0x7685 A 194.94.133.71
397 55.958000000 192.168.1.100 192.168.1.2
DNS 101 Standard query response 0xdede A 134.130.184.19
499 56.414273000 192.168.1.2 192.168.1.100
DNS 92 Standard query 0xc7ad A katalog.bibl.fh-duesseldorf.de
500 56.415217000 192.168.1.100 192.168.1.2
DNS 108 Standard query response 0xc7ad A 195.37.241.41
629 57.026770000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0xb8a3 A identity.fu-berlin.de
631 57.027666000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0xb8a3 A 130.133.3.11
781 57.733148000 192.168.1.2 192.168.1.100
DNS 92 Standard query 0x9424 A katalog.bibl.fh-duesseldorf.de
782 57.733956000 192.168.1.100 192.168.1.2
DNS 108 Standard query response 0x9424 A 195.37.241.41
897 58.312720000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0x89f1 A opac.hu-berlin.de
900 58.313866000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0x89f1 CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
901 58.313922000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0xc285 A aleph.ub.hu-berlin.de
902 58.314682000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0xc285 A 141.20.84.140
1106 59.720782000 192.168.1.2 192.168.1.100
DNS 87 Standard query 0x1b6a A aleph-www.ub.fu-berlin.de
1107 59.721583000 192.168.1.100 192.168.1.2
DNS 103 Standard query response 0x1b6a A 160.45.152.64
1126 59.875618000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0x7943 A opac.hu-berlin.de
1127 59.876441000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0x7943 CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
1128 59.876500000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0x2fc6 A aleph.ub.hu-berlin.de
1129 59.877475000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0x2fc6 A 141.20.84.140
1233 60.576835000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0xbc74 A opac.hu-berlin.de
1234 60.577766000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0xbc74 CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
1235 60.577810000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0x3791 A aleph.ub.hu-berlin.de
1236 60.578580000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0x3791 A 141.20.84.140
1239 60.637010000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0x229e AAAA
ausleihe.staatsbibliothek-berlin.de
1240 60.637020000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x2204 AAAA was.duesseldorf.de
1241 60.639789000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x269c AAAA was.duesseldorf.de
1250 60.802820000 192.168.1.100 192.168.1.2
DNS 162 Standard query response 0x229e
1251 60.802910000 192.168.1.2 192.168.1.100
DNS 97 Standard query 0x389d A ausleihe.staatsbibliothek-berlin.de
1252 60.803701000 192.168.1.100 192.168.1.2
DNS 113 Standard query response 0x389d A 194.94.133.71
1255 60.810916000 192.168.1.100 192.168.1.2
DNS 137 Standard query response 0x269c
1256 60.810983000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0x62f1 A was.duesseldorf.de
1257 60.811805000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0x62f1 A 194.113.247.117
1341 62.301664000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0xe7ae A opac.hu-berlin.de
1342 62.302492000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0xe7ae CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
1343 62.302605000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0x735c A aleph.ub.hu-berlin.de
1344 62.303308000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0x735c A 141.20.84.140
1363 62.605245000 192.168.1.2 192.168.1.100
DNS 87 Standard query 0x9c6f A aleph-www.ub.fu-berlin.de
1364 62.606069000 192.168.1.100 192.168.1.2
DNS 103 Standard query response 0x9c6f A 160.45.152.64
1387 62.717863000 192.168.1.2 192.168.1.100
DNS 79 Standard query 0xe7b2 A opac.hu-berlin.de
1388 62.718670000 192.168.1.100 192.168.1.2
DNS 118 Standard query response 0xe7b2 CNAME
aleph.ub.hu-berlin.de A 141.20.84.140
1389 62.719429000 192.168.1.2 192.168.1.100
DNS 83 Standard query 0x190f A aleph.ub.hu-berlin.de
1390 62.720117000 192.168.1.100 192.168.1.2
DNS 99 Standard query response 0x190f A 141.20.84.140
1453 65.644751000 192.168.1.2 192.168.1.100
DNS 80 Standard query 0xf8aa A was.duesseldorf.de
1454 65.645566000 192.168.1.100 192.168.1.2
DNS 96 Standard query response 0xf8aa A 194.113.247.117
However, it does work fine, if I run it in single threaded mode
manually, waiting for a connection to close, before opening the next one.
So it seems the router "forgets" the dns query, if there is another
query for the same host in the same second.
But there surely are many router like that, and synapse should work .
So how can we make it more robust?
Try the DNS request again, if the first fails?
Wait for a reply, before sending any new quest, synchronized among all
threads?
Cache all queries from all threads, and only send one query for each host?
Benito
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