forked from dmlc/xgboost
-
Notifications
You must be signed in to change notification settings - Fork 0
/
allreduce_base.cc
986 lines (958 loc) · 34.6 KB
/
allreduce_base.cc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
/*!
* Copyright (c) 2014 by Contributors
* \file allreduce_base.cc
* \brief Basic implementation of AllReduce
*
* \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
*/
#if !defined(NOMINMAX) && defined(_WIN32)
#define NOMINMAX
#endif // !defined(NOMINMAX)
#include "rabit/base.h"
#include "rabit/internal/rabit-inl.h"
#include "allreduce_base.h"
#ifndef _WIN32
#include <netinet/tcp.h>
#endif // _WIN32
#include <cstring>
#include <map>
namespace rabit {
namespace engine {
// constructor
AllreduceBase::AllreduceBase() {
tracker_uri = "NULL";
tracker_port = 9000;
host_uri = "";
slave_port = 9010;
nport_trial = 1000;
rank = 0;
world_size = -1;
connect_retry = 5;
hadoop_mode = false;
version_number = 0;
// 32 K items
reduce_ring_mincount = 32 << 10;
// 1M reducer size each time
tree_reduce_minsize = 1 << 20;
// tracker URL
task_id = "NULL";
err_link = nullptr;
dmlc_role = "worker";
this->SetParam("rabit_reduce_buffer", "256MB");
// setup possible environment variable of interest
// include dmlc support direct variables
env_vars.emplace_back("DMLC_TASK_ID");
env_vars.emplace_back("DMLC_ROLE");
env_vars.emplace_back("DMLC_NUM_ATTEMPT");
env_vars.emplace_back("DMLC_TRACKER_URI");
env_vars.emplace_back("DMLC_TRACKER_PORT");
env_vars.emplace_back("DMLC_WORKER_CONNECT_RETRY");
}
// initialization function
bool AllreduceBase::Init(int argc, char* argv[]) {
// setup from environment variables
// handler to get variables from env
for (auto & env_var : env_vars) {
const char *value = getenv(env_var.c_str());
if (value != nullptr) {
this->SetParam(env_var.c_str(), value);
}
}
// pass in arguments override env variable.
for (int i = 0; i < argc; ++i) {
char name[256], val[256];
if (sscanf(argv[i], "%[^=]=%s", name, val) == 2) {
this->SetParam(name, val);
}
}
{
// handling for hadoop
const char *task_id = getenv("mapred_tip_id");
if (task_id == nullptr) {
task_id = getenv("mapreduce_task_id");
}
if (hadoop_mode) {
utils::Check(task_id != nullptr,
"hadoop_mode is set but cannot find mapred_task_id");
}
if (task_id != nullptr) {
this->SetParam("rabit_task_id", task_id);
this->SetParam("rabit_hadoop_mode", "1");
}
const char *attempt_id = getenv("mapred_task_id");
if (attempt_id != nullptr) {
const char *att = strrchr(attempt_id, '_');
int num_trial;
if (att != nullptr && sscanf(att + 1, "%d", &num_trial) == 1) {
this->SetParam("rabit_num_trial", att + 1);
}
}
// handling for hadoop
const char *num_task = getenv("mapred_map_tasks");
if (num_task == nullptr) {
num_task = getenv("mapreduce_job_maps");
}
if (hadoop_mode) {
utils::Check(num_task != nullptr,
"hadoop_mode is set but cannot find mapred_map_tasks");
}
if (num_task != nullptr) {
this->SetParam("rabit_world_size", num_task);
}
}
if (dmlc_role != "worker") {
LOG(FATAL) << "Rabit Module currently only work with dmlc worker";
}
// clear the setting before start reconnection
this->rank = -1;
//---------------------
// start socket
utils::Socket::Startup();
utils::Assert(all_links.size() == 0, "can only call Init once");
this->host_uri = utils::SockAddr::GetHostName();
// get information from tracker
return this->ReConnectLinks();
}
bool AllreduceBase::Shutdown() {
try {
for (auto & all_link : all_links) {
if (!all_link.sock.IsClosed()) {
all_link.sock.Close();
}
}
all_links.clear();
tree_links.plinks.clear();
if (tracker_uri == "NULL") return true;
// notify tracker rank i have shutdown
utils::TCPSocket tracker = this->ConnectTracker();
tracker.SendStr(std::string("shutdown"));
tracker.Close();
utils::TCPSocket::Finalize();
return true;
} catch (const std::exception& e) {
LOG(WARNING) << "Failed to shutdown due to" << e.what();
return false;
}
}
void AllreduceBase::TrackerPrint(const std::string &msg) {
if (tracker_uri == "NULL") {
utils::Printf("%s", msg.c_str()); return;
}
utils::TCPSocket tracker = this->ConnectTracker();
tracker.SendStr(std::string("print"));
tracker.SendStr(msg);
tracker.Close();
}
// util to parse data with unit suffix
inline size_t ParseUnit(const char *name, const char *val) {
char unit;
unsigned long amt; // NOLINT(*)
int n = sscanf(val, "%lu%c", &amt, &unit);
size_t amount = amt;
if (n == 2) {
switch (unit) {
case 'B': return amount;
case 'K': return amount << 10UL;
case 'M': return amount << 20UL;
case 'G': return amount << 30UL;
default: utils::Error("invalid format for %s", name); return 0;
}
} else if (n == 1) {
return amount;
} else {
utils::Error("invalid format for %s," \
"shhould be {integer}{unit}, unit can be {B, KB, MB, GB}", name);
return 0;
}
}
/*!
* \brief set parameters to the engine
* \param name parameter name
* \param val parameter value
*/
void AllreduceBase::SetParam(const char *name, const char *val) {
if (!strcmp(name, "rabit_tracker_uri")) tracker_uri = val;
if (!strcmp(name, "rabit_tracker_port")) tracker_port = atoi(val);
if (!strcmp(name, "rabit_task_id")) task_id = val;
if (!strcmp(name, "DMLC_TRACKER_URI")) tracker_uri = val;
if (!strcmp(name, "DMLC_TRACKER_PORT")) tracker_port = atoi(val);
if (!strcmp(name, "DMLC_TASK_ID")) task_id = val;
if (!strcmp(name, "DMLC_ROLE")) dmlc_role = val;
if (!strcmp(name, "rabit_world_size")) world_size = atoi(val);
if (!strcmp(name, "rabit_hadoop_mode")) hadoop_mode = utils::StringToBool(val);
if (!strcmp(name, "rabit_tree_reduce_minsize")) tree_reduce_minsize = atoi(val);
if (!strcmp(name, "rabit_reduce_ring_mincount")) {
reduce_ring_mincount = atoi(val);
utils::Assert(reduce_ring_mincount > 0, "rabit_reduce_ring_mincount should be greater than 0");
}
if (!strcmp(name, "rabit_reduce_buffer")) {
reduce_buffer_size = (ParseUnit(name, val) + 7) >> 3;
}
if (!strcmp(name, "DMLC_WORKER_CONNECT_RETRY")) {
connect_retry = atoi(val);
}
if (!strcmp(name, "rabit_bootstrap_cache")) {
rabit_bootstrap_cache = utils::StringToBool(val);
}
if (!strcmp(name, "rabit_debug")) {
rabit_debug = utils::StringToBool(val);
}
if (!strcmp(name, "rabit_timeout")) {
rabit_timeout = utils::StringToBool(val);
}
if (!strcmp(name, "rabit_timeout_sec")) {
timeout_sec = std::chrono::seconds(atoi(val));
utils::Assert(timeout_sec.count() >= 0, "rabit_timeout_sec should be non negative second");
}
if (!strcmp(name, "rabit_enable_tcp_no_delay")) {
if (!strcmp(val, "true")) {
rabit_enable_tcp_no_delay = true;
} else {
rabit_enable_tcp_no_delay = false;
}
}
}
/*!
* \brief initialize connection to the tracker
* \return a socket that initializes the connection
*/
utils::TCPSocket AllreduceBase::ConnectTracker() const {
int magic = kMagic;
// get information from tracker
utils::TCPSocket tracker;
tracker.Create();
int retry = 0;
do {
if (!tracker.Connect(utils::SockAddr(tracker_uri.c_str(), tracker_port))) {
if (++retry >= connect_retry) {
LOG(WARNING) << "Connect to (failed): [" << tracker_uri << "]\n";
utils::Socket::Error("Connect");
} else {
LOG(WARNING) << "Retry connect to ip(retry time " << retry << "): [" << tracker_uri << "]\n";
#if defined(_MSC_VER) || defined (__MINGW32__)
Sleep(retry << 1);
#else
sleep(retry << 1);
#endif
continue;
}
}
break;
} while (true);
using utils::Assert;
Assert(tracker.SendAll(&magic, sizeof(magic)) == sizeof(magic),
"ReConnectLink failure 1");
Assert(tracker.RecvAll(&magic, sizeof(magic)) == sizeof(magic),
"ReConnectLink failure 2");
utils::Check(magic == kMagic, "sync::Invalid tracker message, init failure");
Assert(tracker.SendAll(&rank, sizeof(rank)) == sizeof(rank),
"ReConnectLink failure 3");
Assert(tracker.SendAll(&world_size, sizeof(world_size)) == sizeof(world_size),
"ReConnectLink failure 3");
tracker.SendStr(task_id);
return tracker;
}
/*!
* \brief connect to the tracker to fix the the missing links
* this function is also used when the engine start up
*/
bool AllreduceBase::ReConnectLinks(const char *cmd) {
// single node mode
if (tracker_uri == "NULL") {
rank = 0; world_size = 1; return true;
}
try {
utils::TCPSocket tracker = this->ConnectTracker();
LOG(INFO) << "task " << task_id << " connected to the tracker";
tracker.SendStr(std::string(cmd));
// the rank of previous link, next link in ring
int prev_rank, next_rank;
// the rank of neighbors
std::map<int, int> tree_neighbors;
using utils::Assert;
// get new ranks
int newrank, num_neighbors;
Assert(tracker.RecvAll(&newrank, sizeof(newrank)) == sizeof(newrank),
"ReConnectLink failure 4");
Assert(tracker.RecvAll(&parent_rank, sizeof(parent_rank)) == \
sizeof(parent_rank), "ReConnectLink failure 4");
Assert(tracker.RecvAll(&world_size, sizeof(world_size)) == sizeof(world_size),
"ReConnectLink failure 4");
Assert(rank == -1 || newrank == rank,
"must keep rank to same if the node already have one");
rank = newrank;
if (rank == -1) {
LOG(FATAL) << "tracker got overwhelmed and not able to assign correct rank";
}
LOG(CONSOLE) << "task " << task_id << " got new rank " << rank;
Assert(tracker.RecvAll(&num_neighbors, sizeof(num_neighbors)) == \
sizeof(num_neighbors), "ReConnectLink failure 4");
for (int i = 0; i < num_neighbors; ++i) {
int nrank;
Assert(tracker.RecvAll(&nrank, sizeof(nrank)) == sizeof(nrank),
"ReConnectLink failure 4");
tree_neighbors[nrank] = 1;
}
Assert(tracker.RecvAll(&prev_rank, sizeof(prev_rank)) == sizeof(prev_rank),
"ReConnectLink failure 4");
Assert(tracker.RecvAll(&next_rank, sizeof(next_rank)) == sizeof(next_rank),
"ReConnectLink failure 4");
utils::TCPSocket sock_listen;
if (!sock_listen.IsClosed()) {
sock_listen.Close();
}
// create listening socket
sock_listen.Create();
int port = sock_listen.TryBindHost(slave_port, slave_port + nport_trial);
utils::Check(port != -1, "ReConnectLink fail to bind the ports specified");
sock_listen.Listen();
// get number of to connect and number of to accept nodes from tracker
int num_conn, num_accept, num_error = 1;
do {
// send over good links
std::vector<int> good_link;
for (auto & all_link : all_links) {
if (!all_link.sock.BadSocket()) {
good_link.push_back(static_cast<int>(all_link.rank));
} else {
if (!all_link.sock.IsClosed()) all_link.sock.Close();
}
}
int ngood = static_cast<int>(good_link.size());
Assert(tracker.SendAll(&ngood, sizeof(ngood)) == sizeof(ngood),
"ReConnectLink failure 5");
for (int & i : good_link) {
Assert(tracker.SendAll(&i, sizeof(i)) == \
sizeof(i), "ReConnectLink failure 6");
}
Assert(tracker.RecvAll(&num_conn, sizeof(num_conn)) == sizeof(num_conn),
"ReConnectLink failure 7");
Assert(tracker.RecvAll(&num_accept, sizeof(num_accept)) == \
sizeof(num_accept), "ReConnectLink failure 8");
num_error = 0;
for (int i = 0; i < num_conn; ++i) {
LinkRecord r;
int hport, hrank;
std::string hname;
tracker.RecvStr(&hname);
Assert(tracker.RecvAll(&hport, sizeof(hport)) == sizeof(hport),
"ReConnectLink failure 9");
Assert(tracker.RecvAll(&hrank, sizeof(hrank)) == sizeof(hrank),
"ReConnectLink failure 10");
r.sock.Create();
if (!r.sock.Connect(utils::SockAddr(hname.c_str(), hport))) {
num_error += 1;
r.sock.Close();
continue;
}
Assert(r.sock.SendAll(&rank, sizeof(rank)) == sizeof(rank),
"ReConnectLink failure 12");
Assert(r.sock.RecvAll(&r.rank, sizeof(r.rank)) == sizeof(r.rank),
"ReConnectLink failure 13");
utils::Check(hrank == r.rank,
"ReConnectLink failure, link rank inconsistent");
bool match = false;
for (auto & all_link : all_links) {
if (all_link.rank == hrank) {
Assert(all_link.sock.IsClosed(),
"Override a link that is active");
all_link.sock = r.sock;
match = true;
break;
}
}
if (!match) all_links.push_back(r);
}
Assert(tracker.SendAll(&num_error, sizeof(num_error)) == sizeof(num_error),
"ReConnectLink failure 14");
} while (num_error != 0);
// send back socket listening port to tracker
Assert(tracker.SendAll(&port, sizeof(port)) == sizeof(port),
"ReConnectLink failure 14");
// close connection to tracker
tracker.Close();
// listen to incoming links
for (int i = 0; i < num_accept; ++i) {
LinkRecord r;
r.sock = sock_listen.Accept();
Assert(r.sock.SendAll(&rank, sizeof(rank)) == sizeof(rank),
"ReConnectLink failure 15");
Assert(r.sock.RecvAll(&r.rank, sizeof(r.rank)) == sizeof(r.rank),
"ReConnectLink failure 15");
bool match = false;
for (auto & all_link : all_links) {
if (all_link.rank == r.rank) {
utils::Assert(all_link.sock.IsClosed(),
"Override a link that is active");
all_link.sock = r.sock;
match = true;
break;
}
}
if (!match) all_links.push_back(r);
}
sock_listen.Close();
this->parent_index = -1;
// setup tree links and ring structure
tree_links.plinks.clear();
int tcpNoDelay = 1;
for (auto & all_link : all_links) {
utils::Assert(!all_link.sock.BadSocket(), "ReConnectLink: bad socket");
// set the socket to non-blocking mode, enable TCP keepalive
all_link.sock.SetNonBlock(true);
all_link.sock.SetKeepAlive(true);
if (rabit_enable_tcp_no_delay) {
#if defined(__unix__)
setsockopt(all_link.sock, IPPROTO_TCP,
TCP_NODELAY, reinterpret_cast<void *>(&tcpNoDelay), sizeof(tcpNoDelay));
#else
LOG(WARNING) << "tcp no delay is not implemented on non unix platforms";
#endif
}
if (tree_neighbors.count(all_link.rank) != 0) {
if (all_link.rank == parent_rank) {
parent_index = static_cast<int>(tree_links.plinks.size());
}
tree_links.plinks.push_back(&all_link);
}
if (all_link.rank == prev_rank) ring_prev = &all_link;
if (all_link.rank == next_rank) ring_next = &all_link;
}
Assert(parent_rank == -1 || parent_index != -1,
"cannot find parent in the link");
Assert(prev_rank == -1 || ring_prev != nullptr,
"cannot find prev ring in the link");
Assert(next_rank == -1 || ring_next != nullptr,
"cannot find next ring in the link");
return true;
} catch (const std::exception& e) {
LOG(WARNING) << "failed in ReconnectLink " << e.what();
return false;
}
}
/*!
* \brief perform in-place allreduce, on sendrecvbuf, this function can fail, and will return the cause of failure
*
* NOTE on Allreduce:
* The kSuccess TryAllreduce does NOT mean every node have successfully finishes TryAllreduce.
* It only means the current node get the correct result of Allreduce.
* However, it means every node finishes LAST call(instead of this one) of Allreduce/Bcast
*
* \param sendrecvbuf_ buffer for both sending and receiving data
* \param type_nbytes the unit number of bytes the type have
* \param count number of elements to be reduced
* \param reducer reduce function
* \return this function can return kSuccess, kSockError, kGetExcept, see ReturnType for details
* \sa ReturnType
*/
AllreduceBase::ReturnType
AllreduceBase::TryAllreduce(void *sendrecvbuf_,
size_t type_nbytes,
size_t count,
ReduceFunction reducer) {
if (count > reduce_ring_mincount) {
return this->TryAllreduceRing(sendrecvbuf_, type_nbytes, count, reducer);
} else {
return this->TryAllreduceTree(sendrecvbuf_, type_nbytes, count, reducer);
}
}
/*!
* \brief perform in-place allreduce, on sendrecvbuf,
* this function implements tree-shape reduction
*
* \param sendrecvbuf_ buffer for both sending and receiving data
* \param type_nbytes the unit number of bytes the type have
* \param count number of elements to be reduced
* \param reducer reduce function
* \return this function can return kSuccess, kSockError, kGetExcept, see ReturnType for details
* \sa ReturnType
*/
AllreduceBase::ReturnType
AllreduceBase::TryAllreduceTree(void *sendrecvbuf_,
size_t type_nbytes,
size_t count,
ReduceFunction reducer) {
RefLinkVector &links = tree_links;
if (links.Size() == 0 || count == 0) return kSuccess;
// total size of message
const size_t total_size = type_nbytes * count;
// number of links
const int nlink = static_cast<int>(links.Size());
// send recv buffer
char *sendrecvbuf = reinterpret_cast<char*>(sendrecvbuf_);
// size of space that we already performs reduce in up pass
size_t size_up_reduce = 0;
// size of space that we have already passed to parent
size_t size_up_out = 0;
// size of message we received, and send in the down pass
size_t size_down_in = 0;
// minimal size of each reducer
const size_t eachreduce = (tree_reduce_minsize / type_nbytes * type_nbytes);
// initialize the link ring-buffer and pointer
for (int i = 0; i < nlink; ++i) {
if (i != parent_index) {
links[i].InitBuffer(type_nbytes, count, reduce_buffer_size);
}
links[i].ResetSize();
}
// if no children, no need to reduce
if (nlink == static_cast<int>(parent_index != -1)) {
size_up_reduce = total_size;
}
// while we have not passed the messages out
while (true) {
// select helper
bool finished = true;
utils::PollHelper watcher;
for (int i = 0; i < nlink; ++i) {
if (i == parent_index) {
if (size_down_in != total_size) {
watcher.WatchRead(links[i].sock);
// only watch for exception in live channels
watcher.WatchException(links[i].sock);
finished = false;
}
if (size_up_out != total_size && size_up_out < size_up_reduce) {
watcher.WatchWrite(links[i].sock);
}
} else {
if (links[i].size_read != total_size) {
watcher.WatchRead(links[i].sock);
}
// size_write <= size_read
if (links[i].size_write != total_size) {
if (links[i].size_write < size_down_in) {
watcher.WatchWrite(links[i].sock);
}
// only watch for exception in live channels
watcher.WatchException(links[i].sock);
finished = false;
}
}
}
// finish running allreduce
if (finished) break;
// select must return
watcher.Poll(timeout_sec);
// read data from childs
for (int i = 0; i < nlink; ++i) {
if (i != parent_index && watcher.CheckRead(links[i].sock)) {
// make sure to receive minimal reducer size
// since each child reduce and sends the minimal reducer size
while (links[i].size_read < total_size
&& links[i].size_read - size_up_reduce < eachreduce) {
ReturnType ret = links[i].ReadToRingBuffer(size_up_out, total_size);
if (ret != kSuccess) {
return ReportError(&links[i], ret);
}
}
}
}
// this node have children, perform reduce
if (nlink > static_cast<int>(parent_index != -1)) {
size_t buffer_size = 0;
// do upstream reduce
size_t max_reduce = total_size;
for (int i = 0; i < nlink; ++i) {
if (i != parent_index) {
max_reduce = std::min(max_reduce, links[i].size_read);
utils::Assert(buffer_size == 0 || buffer_size == links[i].buffer_size,
"buffer size inconsistent");
buffer_size = links[i].buffer_size;
}
}
utils::Assert(buffer_size != 0, "must assign buffer_size");
// round to type_n4bytes
max_reduce = (max_reduce / type_nbytes * type_nbytes);
// if max reduce is less than total size, we reduce multiple times of
// each reduce size
if (max_reduce < total_size) {
max_reduce = max_reduce - max_reduce % eachreduce;
}
// perform reduce, can be at most two rounds
while (size_up_reduce < max_reduce) {
// start position
size_t start = size_up_reduce % buffer_size;
// perform read till end of buffer
size_t nread = std::min(buffer_size - start,
max_reduce - size_up_reduce);
utils::Assert(nread % type_nbytes == 0, "Allreduce: size check");
for (int i = 0; i < nlink; ++i) {
if (i != parent_index) {
reducer(links[i].buffer_head + start,
sendrecvbuf + size_up_reduce,
static_cast<int>(nread / type_nbytes),
MPI::Datatype(type_nbytes));
}
}
size_up_reduce += nread;
}
}
if (parent_index != -1) {
// pass message up to parent, can pass data that are already been reduced
if (size_up_out < size_up_reduce) {
ssize_t len = links[parent_index].sock.
Send(sendrecvbuf + size_up_out, size_up_reduce - size_up_out);
if (len != -1) {
size_up_out += static_cast<size_t>(len);
} else {
ReturnType ret = Errno2Return();
if (ret != kSuccess) {
return ReportError(&links[parent_index], ret);
}
}
}
// read data from parent
if (watcher.CheckRead(links[parent_index].sock) &&
total_size > size_down_in) {
size_t left_size = total_size-size_down_in;
size_t reduce_size_min = std::min(left_size, eachreduce);
size_t recved = 0;
while (recved < reduce_size_min) {
ssize_t len = links[parent_index].sock.
Recv(sendrecvbuf + size_down_in, total_size - size_down_in);
if (len == 0) {
links[parent_index].sock.Close();
return ReportError(&links[parent_index], kRecvZeroLen);
}
if (len != -1) {
size_down_in += static_cast<size_t>(len);
utils::Assert(size_down_in <= size_up_out,
"Allreduce: boundary error");
recved+=len;
// if it receives more data than each reduce, it means the next block is sent.
// we double the reduce_size_min or add to left_size
while (recved > reduce_size_min) {
reduce_size_min += std::min(left_size-reduce_size_min, eachreduce);
}
} else {
ReturnType ret = Errno2Return();
if (ret != kSuccess) {
return ReportError(&links[parent_index], ret);
}
}
}
}
} else {
// this is root, can use reduce as most recent point
size_down_in = size_up_out = size_up_reduce;
}
// can pass message down to children
for (int i = 0; i < nlink; ++i) {
if (i != parent_index && links[i].size_write < size_down_in) {
ReturnType ret = links[i].WriteFromArray(sendrecvbuf, size_down_in);
if (ret != kSuccess) {
return ReportError(&links[i], ret);
}
}
}
}
return kSuccess;
}
/*!
* \brief broadcast data from root to all nodes, this function can fail,and will return the cause of failure
* \param sendrecvbuf_ buffer for both sending and receiving data
* \param total_size the size of the data to be broadcasted
* \param root the root worker id to broadcast the data
* \return this function can return kSuccess, kSockError, kGetExcept, see ReturnType for details
* \sa ReturnType
*/
AllreduceBase::ReturnType
AllreduceBase::TryBroadcast(void *sendrecvbuf_, size_t total_size, int root) {
RefLinkVector &links = tree_links;
if (links.Size() == 0 || total_size == 0) return kSuccess;
utils::Check(root < world_size,
"Broadcast: root should be smaller than world size");
// number of links
const int nlink = static_cast<int>(links.Size());
// size of space already read from data
size_t size_in = 0;
// input link, -2 means unknown yet, -1 means this is root
int in_link = -2;
// initialize the link statistics
for (int i = 0; i < nlink; ++i) {
links[i].ResetSize();
}
// root have all the data
if (this->rank == root) {
size_in = total_size;
in_link = -1;
}
// while we have not passed the messages out
while (true) {
bool finished = true;
// select helper
utils::PollHelper watcher;
for (int i = 0; i < nlink; ++i) {
if (in_link == -2) {
watcher.WatchRead(links[i].sock); finished = false;
}
if (i == in_link && links[i].size_read != total_size) {
watcher.WatchRead(links[i].sock); finished = false;
}
if (in_link != -2 && i != in_link && links[i].size_write != total_size) {
if (links[i].size_write < size_in) {
watcher.WatchWrite(links[i].sock);
}
finished = false;
}
watcher.WatchException(links[i].sock);
}
// finish running
if (finished) break;
// select
watcher.Poll(timeout_sec);
if (in_link == -2) {
// probe in-link
for (int i = 0; i < nlink; ++i) {
if (watcher.CheckRead(links[i].sock)) {
ReturnType ret = links[i].ReadToArray(sendrecvbuf_, total_size);
if (ret != kSuccess) {
return ReportError(&links[i], ret);
}
size_in = links[i].size_read;
if (size_in != 0) {
in_link = i; break;
}
}
}
} else {
// read from in link
if (in_link >= 0 && watcher.CheckRead(links[in_link].sock)) {
ReturnType ret = links[in_link].ReadToArray(sendrecvbuf_, total_size);
if (ret != kSuccess) {
return ReportError(&links[in_link], ret);
}
size_in = links[in_link].size_read;
}
}
// send data to all out-link
for (int i = 0; i < nlink; ++i) {
if (i != in_link && links[i].size_write < size_in) {
ReturnType ret = links[i].WriteFromArray(sendrecvbuf_, size_in);
if (ret != kSuccess) {
return ReportError(&links[i], ret);
}
}
}
}
return kSuccess;
}
/*!
* \brief internal Allgather function, each node have a segment of data in the ring of sendrecvbuf,
* the data provided by current node k is [slice_begin, slice_end),
* the next node's segment must start with slice_end
* after the call of Allgather, sendrecvbuf_ contains all the contents including all segments
* use a ring based algorithm
*
* \param sendrecvbuf_ buffer for both sending and receiving data, it is a ring conceptually
* \param total_size total size of data to be gathered
* \param slice_begin beginning of the current slice
* \param slice_end end of the current slice
* \param size_prev_slice size of the previous slice i.e. slice of node (rank - 1) % world_size
*/
AllreduceBase::ReturnType
AllreduceBase::TryAllgatherRing(void *sendrecvbuf_, size_t total_size,
size_t slice_begin,
size_t slice_end,
size_t size_prev_slice) {
// read from next link and send to prev one
LinkRecord &prev = *ring_prev, &next = *ring_next;
// need to reply on special rank structure
utils::Assert(next.rank == (rank + 1) % world_size &&
rank == (prev.rank + 1) % world_size,
"need to assume rank structure");
// send recv buffer
char *sendrecvbuf = reinterpret_cast<char*>(sendrecvbuf_);
const size_t stop_read = total_size + slice_begin;
const size_t stop_write = total_size + slice_begin - size_prev_slice;
size_t write_ptr = slice_begin;
size_t read_ptr = slice_end;
while (true) {
// select helper
bool finished = true;
utils::PollHelper watcher;
if (read_ptr != stop_read) {
watcher.WatchRead(next.sock);
finished = false;
}
if (write_ptr != stop_write) {
if (write_ptr < read_ptr) {
watcher.WatchWrite(prev.sock);
}
finished = false;
}
if (finished) break;
watcher.Poll(timeout_sec);
if (read_ptr != stop_read && watcher.CheckRead(next.sock)) {
size_t size = stop_read - read_ptr;
size_t start = read_ptr % total_size;
if (start + size > total_size) {
size = total_size - start;
}
ssize_t len = next.sock.Recv(sendrecvbuf + start, size);
if (len != -1) {
read_ptr += static_cast<size_t>(len);
} else {
ReturnType ret = Errno2Return();
if (ret != kSuccess) {
auto err = ReportError(&next, ret);
return err;
}
}
}
if (write_ptr < read_ptr && write_ptr != stop_write) {
size_t size = std::min(read_ptr, stop_write) - write_ptr;
size_t start = write_ptr % total_size;
if (start + size > total_size) {
size = total_size - start;
}
ssize_t len = prev.sock.Send(sendrecvbuf + start, size);
if (len != -1) {
write_ptr += static_cast<size_t>(len);
} else {
ReturnType ret = Errno2Return();
if (ret != kSuccess) {
auto err = ReportError(&prev, ret);
return err;
}
}
}
}
return kSuccess;
}
/*!
* \brief perform in-place allreduce, on sendrecvbuf, this function can fail,
* and will return the cause of failure
*
* Ring-based algorithm
*
* \param sendrecvbuf_ buffer for both sending and receiving data
* \param type_nbytes the unit number of bytes the type have
* \param count number of elements to be reduced
* \param reducer reduce function
* \return this function can return kSuccess, kSockError, kGetExcept, see ReturnType for details
* \sa ReturnType, TryAllreduce
*/
AllreduceBase::ReturnType
AllreduceBase::TryReduceScatterRing(void *sendrecvbuf_,
size_t type_nbytes,
size_t count,
ReduceFunction reducer) {
// read from next link and send to prev one
LinkRecord &prev = *ring_prev, &next = *ring_next;
// need to reply on special rank structure
utils::Assert(next.rank == (rank + 1) % world_size &&
rank == (prev.rank + 1) % world_size,
"need to assume rank structure");
// total size of message
const size_t total_size = type_nbytes * count;
size_t n = static_cast<size_t>(world_size);
size_t step = (count + n - 1) / n;
size_t r = static_cast<size_t>(next.rank);
size_t write_ptr = std::min(r * step, count) * type_nbytes;
size_t read_ptr = std::min((r + 1) * step, count) * type_nbytes;
size_t reduce_ptr = read_ptr;
// send recv buffer
char *sendrecvbuf = reinterpret_cast<char*>(sendrecvbuf_);
// position to stop reading
const size_t stop_read = total_size + write_ptr;
// position to stop writing
size_t stop_write = total_size + std::min(rank * step, count) * type_nbytes;
if (stop_write > stop_read) {
stop_write -= total_size;
utils::Assert(write_ptr <= stop_write, "write ptr boundary check");
}
// use ring buffer in next position
next.InitBuffer(type_nbytes, step, reduce_buffer_size);
// set size_read to read pointer for ring buffer to work properly
next.size_read = read_ptr;
while (true) {
// select helper
bool finished = true;
utils::PollHelper watcher;
if (read_ptr != stop_read) {
watcher.WatchRead(next.sock);
finished = false;
}
if (write_ptr != stop_write) {
if (write_ptr < reduce_ptr) {
watcher.WatchWrite(prev.sock);
}
finished = false;
}
if (finished) break;
watcher.Poll(timeout_sec);
if (read_ptr != stop_read && watcher.CheckRead(next.sock)) {
ReturnType ret = next.ReadToRingBuffer(reduce_ptr, stop_read);
if (ret != kSuccess) {
return ReportError(&next, ret);
}
// sync the rate
read_ptr = next.size_read;
utils::Assert(read_ptr <= stop_read, "[%d] read_ptr boundary check", rank);
const size_t buffer_size = next.buffer_size;
size_t max_reduce = (read_ptr / type_nbytes) * type_nbytes;
while (reduce_ptr < max_reduce) {
size_t bstart = reduce_ptr % buffer_size;
size_t nread = std::min(buffer_size - bstart,
max_reduce - reduce_ptr);
size_t rstart = reduce_ptr % total_size;
nread = std::min(nread, total_size - rstart);
reducer(next.buffer_head + bstart,
sendrecvbuf + rstart,
static_cast<int>(nread / type_nbytes),
MPI::Datatype(type_nbytes));
reduce_ptr += nread;
}
}
if (write_ptr < reduce_ptr && write_ptr != stop_write) {
size_t size = std::min(reduce_ptr, stop_write) - write_ptr;
size_t start = write_ptr % total_size;
if (start + size > total_size) {
size = total_size - start;
}
ssize_t len = prev.sock.Send(sendrecvbuf + start, size);
if (len != -1) {
write_ptr += static_cast<size_t>(len);
} else {
ReturnType ret = Errno2Return();
if (ret != kSuccess) return ReportError(&prev, ret);
}
}
}
return kSuccess;
}
/*!
* \brief perform in-place allreduce, on sendrecvbuf
* use a ring based algorithm
*
* \param sendrecvbuf_ buffer for both sending and receiving data
* \param type_nbytes the unit number of bytes the type have
* \param count number of elements to be reduced
* \param reducer reduce function
* \return this function can return kSuccess, kSockError, kGetExcept, see ReturnType for details
* \sa ReturnType
*/
AllreduceBase::ReturnType
AllreduceBase::TryAllreduceRing(void *sendrecvbuf_,
size_t type_nbytes,
size_t count,
ReduceFunction reducer) {
ReturnType ret = TryReduceScatterRing(sendrecvbuf_, type_nbytes, count, reducer);
if (ret != kSuccess) return ret;
size_t n = static_cast<size_t>(world_size);
size_t step = (count + n - 1) / n;
size_t begin = std::min(rank * step, count) * type_nbytes;
size_t end = std::min((rank + 1) * step, count) * type_nbytes;
// previous rank
int prank = ring_prev->rank;
// get rank of previous
return TryAllgatherRing
(sendrecvbuf_, type_nbytes * count,
begin, end,
(std::min((prank + 1) * step, count) -
std::min(prank * step, count)) * type_nbytes);
}
} // namespace engine
} // namespace rabit