2
* Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
3
* Copyright (c) 2018, Google and/or its affiliates. All rights reserved.
4
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6
* This code is free software; you can redistribute it and/or modify it
7
* under the terms of the GNU General Public License version 2 only, as
8
* published by the Free Software Foundation.
10
* This code is distributed in the hope that it will be useful, but WITHOUT
11
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13
* version 2 for more details (a copy is included in the LICENSE file that
14
* accompanied this code).
16
* You should have received a copy of the GNU General Public License version
17
* 2 along with this work; if not, write to the Free Software Foundation,
18
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21
* or visit www.oracle.com if you need additional information or have any
26
#include "precompiled.hpp"
27
#include "logging/log.hpp"
28
#include "logging/logTag.hpp"
29
#include "prims/jvmtiExport.hpp"
30
#include "runtime/atomic.hpp"
31
#include "runtime/handles.inline.hpp"
32
#include "runtime/sharedRuntime.hpp"
33
#include "runtime/threadHeapSampler.hpp"
34
#include "utilities/checkedCast.hpp"
36
// Cheap random number generator.
37
uint64_t ThreadHeapSampler::_rnd;
39
volatile int ThreadHeapSampler::_sampling_interval = 512 * 1024;
41
// Statics for the fast log
42
static const int FastLogNumBits = 10;
43
static const int FastLogCount = 1 << FastLogNumBits;
44
static const int FastLogMask = FastLogCount - 1;
45
static const double log_table[FastLogCount] = {46
0.000704269011247, 0.002111776479852, 0.003517912108602, 0.004922678569045,
47
0.006326078524934, 0.007728114632254, 0.009128789539256, 0.010528105886485,
48
0.011926066306808, 0.013322673425448, 0.014717929860010, 0.016111838220512,
49
0.017504401109415, 0.018895621121649, 0.020285500844648, 0.021674042858370,
50
0.023061249735335, 0.024447124040647, 0.025831668332026, 0.027214885159835,
51
0.028596777067108, 0.029977346589579, 0.031356596255709, 0.032734528586714,
52
0.034111146096593, 0.035486451292154, 0.036860446673046, 0.038233134731779,
53
0.039604517953758, 0.040974598817306, 0.042343379793691, 0.043710863347156,
54
0.045077051934941, 0.046441948007312, 0.047805554007589, 0.049167872372170,
55
0.050528905530555, 0.051888655905378, 0.053247125912426, 0.054604317960672,
56
0.055960234452294, 0.057314877782703, 0.058668250340571, 0.060020354507853,
57
0.061371192659811, 0.062720767165044, 0.064069080385509, 0.065416134676548,
58
0.066761932386908, 0.068106475858773, 0.069449767427783, 0.070791809423061,
59
0.072132604167234, 0.073472153976460, 0.074810461160454, 0.076147528022505,
60
0.077483356859507, 0.078817949961979, 0.080151309614087, 0.081483438093674,
61
0.082814337672274, 0.084144010615144, 0.085472459181283, 0.086799685623453,
62
0.088125692188207, 0.089450481115907, 0.090774054640751, 0.092096414990791,
63
0.093417564387961, 0.094737505048093, 0.096056239180946, 0.097373768990222,
64
0.098690096673594, 0.100005224422721, 0.101319154423276, 0.102631888854968,
65
0.103943429891557, 0.105253779700883, 0.106562940444883, 0.107870914279614,
66
0.109177703355275, 0.110483309816226, 0.111787735801012, 0.113090983442381,
67
0.114393054867307, 0.115693952197011, 0.116993677546981, 0.118292233026990,
68
0.119589620741122, 0.120885842787790, 0.122180901259752, 0.123474798244141,
69
0.124767535822473, 0.126059116070680, 0.127349541059119, 0.128638812852598,
70
0.129926933510393, 0.131213905086272, 0.132499729628509, 0.133784409179907,
71
0.135067945777817, 0.136350341454156, 0.137631598235428, 0.138911718142743,
72
0.140190703191836, 0.141468555393084, 0.142745276751529, 0.144020869266892,
73
0.145295334933597, 0.146568675740786, 0.147840893672337, 0.149111990706888,
74
0.150381968817848, 0.151650829973421, 0.152918576136622, 0.154185209265297,
75
0.155450731312137, 0.156715144224702, 0.157978449945432, 0.159240650411673,
76
0.160501747555687, 0.161761743304675, 0.163020639580794, 0.164278438301170,
77
0.165535141377924, 0.166790750718180, 0.168045268224090, 0.169298695792846,
78
0.170551035316700, 0.171802288682983, 0.173052457774115, 0.174301544467631,
79
0.175549550636190, 0.176796478147599, 0.178042328864822, 0.179287104646004,
80
0.180530807344482, 0.181773438808808, 0.183015000882756, 0.184255495405349,
81
0.185494924210866, 0.186733289128866, 0.187970591984199, 0.189206834597024,
82
0.190442018782825, 0.191676146352428, 0.192909219112013, 0.194141238863136,
83
0.195372207402739, 0.196602126523170, 0.197830998012197, 0.199058823653021,
84
0.200285605224298, 0.201511344500146, 0.202736043250167, 0.203959703239463,
85
0.205182326228643, 0.206403913973847, 0.207624468226758, 0.208843990734615,
86
0.210062483240231, 0.211279947482008, 0.212496385193948, 0.213711798105673,
87
0.214926187942435, 0.216139556425135, 0.217351905270334, 0.218563236190271,
88
0.219773550892874, 0.220982851081777, 0.222191138456332, 0.223398414711628,
89
0.224604681538499, 0.225809940623543, 0.227014193649133, 0.228217442293435,
90
0.229419688230416, 0.230620933129866, 0.231821178657404, 0.233020426474497,
91
0.234218678238471, 0.235415935602526, 0.236612200215751, 0.237807473723136,
92
0.239001757765583, 0.240195053979925, 0.241387363998937, 0.242578689451346,
93
0.243769031961852, 0.244958393151134, 0.246146774635865, 0.247334178028729,
94
0.248520604938429, 0.249706056969705, 0.250890535723341, 0.252074042796184,
95
0.253256579781154, 0.254438148267256, 0.255618749839596, 0.256798386079390,
96
0.257977058563978, 0.259154768866840, 0.260331518557602, 0.261507309202055,
97
0.262682142362165, 0.263856019596082, 0.265028942458160, 0.266200912498961,
98
0.267371931265274, 0.268542000300123, 0.269711121142782, 0.270879295328784,
99
0.272046524389938, 0.273212809854334, 0.274378153246363, 0.275542556086722,
100
0.276706019892431, 0.277868546176841, 0.279030136449649, 0.280190792216907,
101
0.281350514981036, 0.282509306240837, 0.283667167491501, 0.284824100224623,
102
0.285980105928212, 0.287135186086704, 0.288289342180970, 0.289442575688332,
103
0.290594888082571, 0.291746280833939, 0.292896755409173, 0.294046313271500,
104
0.295194955880655, 0.296342684692889, 0.297489501160979, 0.298635406734241,
105
0.299780402858540, 0.300924490976300, 0.302067672526519, 0.303209948944775,
106
0.304351321663238, 0.305491792110684, 0.306631361712501, 0.307770031890703,
107
0.308907804063939, 0.310044679647506, 0.311180660053355, 0.312315746690106,
108
0.313449940963058, 0.314583244274195, 0.315715658022202, 0.316847183602472,
109
0.317977822407119, 0.319107575824984, 0.320236445241649, 0.321364432039446,
110
0.322491537597468, 0.323617763291577, 0.324743110494416, 0.325867580575418,
111
0.326991174900817, 0.328113894833656, 0.329235741733800, 0.330356716957943,
112
0.331476821859620, 0.332596057789214, 0.333714426093970, 0.334831928118000,
113
0.335948565202297, 0.337064338684741, 0.338179249900111, 0.339293300180094,
114
0.340406490853295, 0.341518823245243, 0.342630298678407, 0.343740918472201,
115
0.344850683942991, 0.345959596404112, 0.347067657165871, 0.348174867535556,
116
0.349281228817452, 0.350386742312842, 0.351491409320021, 0.352595231134304,
117
0.353698209048035, 0.354800344350596, 0.355901638328417, 0.357002092264984,
118
0.358101707440847, 0.359200485133632, 0.360298426618046, 0.361395533165889,
119
0.362491806046063, 0.363587246524577, 0.364681855864560, 0.365775635326268,
120
0.366868586167093, 0.367960709641570, 0.369052007001388, 0.370142479495399,
121
0.371232128369622, 0.372320954867259, 0.373408960228696, 0.374496145691516,
122
0.375582512490507, 0.376668061857668, 0.377752795022220, 0.378836713210614,
123
0.379919817646538, 0.381002109550926, 0.382083590141966, 0.383164260635110,
124
0.384244122243078, 0.385323176175872, 0.386401423640778, 0.387478865842379,
125
0.388555503982561, 0.389631339260521, 0.390706372872775, 0.391780606013166,
126
0.392854039872873, 0.393926675640417, 0.394998514501672, 0.396069557639868,
127
0.397139806235604, 0.398209261466852, 0.399277924508967, 0.400345796534695,
128
0.401412878714178, 0.402479172214964, 0.403544678202014, 0.404609397837712,
129
0.405673332281866, 0.406736482691724, 0.407798850221975, 0.408860436024760,
130
0.409921241249679, 0.410981267043796, 0.412040514551651, 0.413098984915263,
131
0.414156679274141, 0.415213598765286, 0.416269744523207, 0.417325117679919,
132
0.418379719364956, 0.419433550705378, 0.420486612825775, 0.421538906848277,
133
0.422590433892561, 0.423641195075856, 0.424691191512953, 0.425740424316211,
134
0.426788894595561, 0.427836603458520, 0.428883552010191, 0.429929741353273,
135
0.430975172588069, 0.432019846812492, 0.433063765122069, 0.434106928609955,
136
0.435149338366930, 0.436190995481417, 0.437231901039479, 0.438272056124831,
137
0.439311461818846, 0.440350119200562, 0.441388029346687, 0.442425193331607,
138
0.443461612227394, 0.444497287103809, 0.445532219028312, 0.446566409066067,
139
0.447599858279950, 0.448632567730552, 0.449664538476192, 0.450695771572915,
140
0.451726268074506, 0.452756029032494, 0.453785055496155, 0.454813348512524,
141
0.455840909126398, 0.456867738380343, 0.457893837314700, 0.458919206967592,
142
0.459943848374931, 0.460967762570422, 0.461990950585571, 0.463013413449693,
143
0.464035152189912, 0.465056167831175, 0.466076461396253, 0.467096033905747,
144
0.468114886378099, 0.469133019829591, 0.470150435274359, 0.471167133724392,
145
0.472183116189541, 0.473198383677527, 0.474212937193944, 0.475226777742266,
146
0.476239906323851, 0.477252323937953, 0.478264031581720, 0.479275030250205,
147
0.480285320936372, 0.481294904631098, 0.482303782323183, 0.483311954999353,
148
0.484319423644267, 0.485326189240524, 0.486332252768664, 0.487337615207182,
149
0.488342277532524, 0.489346240719100, 0.490349505739287, 0.491352073563435,
150
0.492353945159870, 0.493355121494907, 0.494355603532845, 0.495355392235982,
151
0.496354488564616, 0.497352893477049, 0.498350607929600, 0.499347632876599,
152
0.500343969270403, 0.501339618061397, 0.502334580197997, 0.503328856626662,
153
0.504322448291891, 0.505315356136237, 0.506307581100306, 0.507299124122766,
154
0.508289986140348, 0.509280168087859, 0.510269670898178, 0.511258495502268,
155
0.512246642829179, 0.513234113806053, 0.514220909358129, 0.515207030408751,
156
0.516192477879367, 0.517177252689541, 0.518161355756956, 0.519144787997414,
157
0.520127550324851, 0.521109643651332, 0.522091068887064, 0.523071826940395,
158
0.524051918717823, 0.525031345124000, 0.526010107061737, 0.526988205432007,
159
0.527965641133954, 0.528942415064895, 0.529918528120324, 0.530893981193921,
160
0.531868775177554, 0.532842910961282, 0.533816389433366, 0.534789211480267,
161
0.535761377986656, 0.536732889835414, 0.537703747907644, 0.538673953082668,
162
0.539643506238036, 0.540612408249530, 0.541580659991169, 0.542548262335212,
163
0.543515216152167, 0.544481522310791, 0.545447181678094, 0.546412195119352,
164
0.547376563498101, 0.548340287676148, 0.549303368513575, 0.550265806868740,
165
0.551227603598288, 0.552188759557150, 0.553149275598548, 0.554109152574003,
166
0.555068391333337, 0.556026992724677, 0.556984957594463, 0.557942286787447,
167
0.558898981146702, 0.559855041513625, 0.560810468727941, 0.561765263627707,
168
0.562719427049319, 0.563672959827513, 0.564625862795372, 0.565578136784329,
169
0.566529782624171, 0.567480801143044, 0.568431193167460, 0.569380959522294,
170
0.570330101030798, 0.571278618514596, 0.572226512793695, 0.573173784686486,
171
0.574120435009748, 0.575066464578656, 0.576011874206780, 0.576956664706092,
172
0.577900836886970, 0.578844391558203, 0.579787329526992, 0.580729651598958,
173
0.581671358578144, 0.582612451267020, 0.583552930466485, 0.584492796975875,
174
0.585432051592962, 0.586370695113965, 0.587308728333545, 0.588246152044817,
175
0.589182967039351, 0.590119174107175, 0.591054774036780, 0.591989767615125,
176
0.592924155627638, 0.593857938858223, 0.594791118089265, 0.595723694101627,
177
0.596655667674663, 0.597587039586216, 0.598517810612622, 0.599447981528719,
178
0.600377553107844, 0.601306526121841, 0.602234901341064, 0.603162679534382,
179
0.604089861469180, 0.605016447911364, 0.605942439625368, 0.606867837374152,
180
0.607792641919210, 0.608716854020573, 0.609640474436812, 0.610563503925040,
181
0.611485943240922, 0.612407793138670, 0.613329054371054, 0.614249727689401,
182
0.615169813843603, 0.616089313582115, 0.617008227651965, 0.617926556798751,
183
0.618844301766652, 0.619761463298424, 0.620678042135410, 0.621594039017540,
184
0.622509454683335, 0.623424289869911, 0.624338545312985, 0.625252221746873,
185
0.626165319904499, 0.627077840517394, 0.627989784315704, 0.628901152028190,
186
0.629811944382234, 0.630722162103839, 0.631631805917638, 0.632540876546891,
187
0.633449374713493, 0.634357301137976, 0.635264656539513, 0.636171441635921,
188
0.637077657143663, 0.637983303777853, 0.638888382252261, 0.639792893279312,
189
0.640696837570094, 0.641600215834357, 0.642503028780520, 0.643405277115674,
190
0.644306961545581, 0.645208082774684, 0.646108641506103, 0.647008638441647,
191
0.647908074281808, 0.648806949725770, 0.649705265471412, 0.650603022215310,
192
0.651500220652738, 0.652396861477678, 0.653292945382815, 0.654188473059545,
193
0.655083445197979, 0.655977862486942, 0.656871725613981, 0.657765035265364,
194
0.658657792126085, 0.659549996879870, 0.660441650209173, 0.661332752795187,
195
0.662223305317840, 0.663113308455806, 0.664002762886501, 0.664891669286088,
196
0.665780028329483, 0.666667840690356, 0.667555107041132, 0.668441828052998,
197
0.669328004395903, 0.670213636738564, 0.671098725748465, 0.671983272091864,
198
0.672867276433793, 0.673750739438063, 0.674633661767266, 0.675516044082778,
199
0.676397887044763, 0.677279191312175, 0.678159957542760, 0.679040186393061,
200
0.679919878518420, 0.680799034572981, 0.681677655209692, 0.682555741080310,
201
0.683433292835402, 0.684310311124349, 0.685186796595348, 0.686062749895414,
202
0.686938171670387, 0.687813062564931, 0.688687423222536, 0.689561254285525,
203
0.690434556395054, 0.691307330191115, 0.692179576312539, 0.693051295396999,
204
0.693922488081015, 0.694793154999950, 0.695663296788022, 0.696532914078300,
205
0.697402007502708, 0.698270577692031, 0.699138625275914, 0.700006150882866,
206
0.700873155140263, 0.701739638674351, 0.702605602110248, 0.703471046071947,
207
0.704335971182319, 0.705200378063116, 0.706064267334970, 0.706927639617403,
208
0.707790495528823, 0.708652835686530, 0.709514660706716, 0.710375971204471,
209
0.711236767793784, 0.712097051087546, 0.712956821697550, 0.713816080234498,
210
0.714674827308002, 0.715533063526583, 0.716390789497679, 0.717248005827646,
211
0.718104713121757, 0.718960911984210, 0.719816603018127, 0.720671786825556,
212
0.721526464007477, 0.722380635163802, 0.723234300893377, 0.724087461793988,
213
0.724940118462359, 0.725792271494157, 0.726643921483994, 0.727495069025431,
214
0.728345714710977, 0.729195859132094, 0.730045502879201, 0.730894646541672,
215
0.731743290707842, 0.732591435965008, 0.733439082899433, 0.734286232096346,
216
0.735132884139946, 0.735979039613404, 0.736824699098865, 0.737669863177453,
217
0.738514532429268, 0.739358707433394, 0.740202388767900, 0.741045577009838,
218
0.741888272735251, 0.742730476519174, 0.743572188935634, 0.744413410557655,
219
0.745254141957257, 0.746094383705463, 0.746934136372297, 0.747773400526791,
220
0.748612176736981, 0.749450465569916, 0.750288267591654, 0.751125583367269,
221
0.751962413460854, 0.752798758435516, 0.753634618853387, 0.754469995275621,
222
0.755304888262399, 0.756139298372928, 0.756973226165448, 0.757806672197228,
223
0.758639637024576, 0.759472121202833, 0.760304125286382, 0.761135649828646,
224
0.761966695382092, 0.762797262498232, 0.763627351727628, 0.764456963619890,
225
0.765286098723682, 0.766114757586723, 0.766942940755785, 0.767770648776705,
226
0.768597882194375, 0.769424641552754, 0.770250927394865, 0.771076740262799,
227
0.771902080697716, 0.772726949239850, 0.773551346428504, 0.774375272802063,
228
0.775198728897986, 0.776021715252813, 0.776844232402167, 0.777666280880755,
229
0.778487861222371, 0.779308973959898, 0.780129619625307, 0.780949798749665,
230
0.781769511863131, 0.782588759494964, 0.783407542173518, 0.784225860426252,
231
0.785043714779724, 0.785861105759600, 0.786678033890652, 0.787494499696761,
232
0.788310503700919, 0.789126046425230, 0.789941128390916, 0.790755750118313,
233
0.791569912126878, 0.792383614935189, 0.793196859060945, 0.794009645020972,
234
0.794821973331222, 0.795633844506778, 0.796445259061850, 0.797256217509785,
235
0.798066720363063, 0.798876768133299, 0.799686361331250, 0.800495500466812,
236
0.801304186049023, 0.802112418586066, 0.802920198585270, 0.803727526553114,
237
0.804534402995225, 0.805340828416384, 0.806146803320525, 0.806952328210736,
238
0.807757403589267, 0.808562029957525, 0.809366207816078, 0.810169937664658,
239
0.810973220002164, 0.811776055326660, 0.812578444135380, 0.813380386924727,
240
0.814181884190280, 0.814982936426790, 0.815783544128185, 0.816583707787570,
241
0.817383427897233, 0.818182704948640, 0.818981539432443, 0.819779931838480,
242
0.820577882655774, 0.821375392372539, 0.822172461476178, 0.822969090453287,
243
0.823765279789659, 0.824561029970280, 0.825356341479334, 0.826151214800207,
244
0.826945650415485, 0.827739648806957, 0.828533210455617, 0.829326335841667,
245
0.830119025444515, 0.830911279742782, 0.831703099214300, 0.832494484336112,
246
0.833285435584481, 0.834075953434884, 0.834866038362018, 0.835655690839800,
247
0.836444911341368, 0.837233700339087, 0.838022058304546, 0.838809985708559,
248
0.839597483021174, 0.840384550711666, 0.841171189248543, 0.841957399099547,
249
0.842743180731658, 0.843528534611089, 0.844313461203296, 0.845097960972975,
250
0.845882034384061, 0.846665681899738, 0.847448903982432, 0.848231701093818,
251
0.849014073694819, 0.849796022245609, 0.850577547205614, 0.851358649033513,
252
0.852139328187243, 0.852919585123995, 0.853699420300221, 0.854478834171630,
253
0.855257827193196, 0.856036399819156, 0.856814552503010, 0.857592285697526,
254
0.858369599854740, 0.859146495425959, 0.859922972861758, 0.860699032611988,
255
0.861474675125773, 0.862249900851513, 0.863024710236886, 0.863799103728850,
256
0.864573081773641, 0.865346644816780, 0.866119793303070, 0.866892527676600,
257
0.867664848380745, 0.868436755858169, 0.869208250550826, 0.869979332899962,
258
0.870750003346114, 0.871520262329114, 0.872290110288090, 0.873059547661470,
259
0.873828574886976, 0.874597192401634, 0.875365400641771, 0.876133200043017,
260
0.876900591040306, 0.877667574067881, 0.878434149559290, 0.879200317947393,
261
0.879966079664357, 0.880731435141664, 0.881496384810110, 0.882260929099804,
262
0.883025068440173, 0.883788803259962, 0.884552133987234, 0.885315061049376,
263
0.886077584873094, 0.886839705884419, 0.887601424508708, 0.888362741170644,
264
0.889123656294237, 0.889884170302829, 0.890644283619089, 0.891403996665022,
265
0.892163309861966, 0.892922223630591, 0.893680738390908, 0.894438854562262,
266
0.895196572563340, 0.895953892812168, 0.896710815726115, 0.897467341721893,
267
0.898223471215558, 0.898979204622514, 0.899734542357511, 0.900489484834649,
268
0.901244032467376, 0.901998185668496, 0.902751944850161, 0.903505310423880,
269
0.904258282800518, 0.905010862390296, 0.905763049602793, 0.906514844846950,
270
0.907266248531065, 0.908017261062803, 0.908767882849189, 0.909518114296615,
271
0.910267955810839, 0.911017407796985, 0.911766470659550, 0.912515144802397,
272
0.913263430628762, 0.914011328541254, 0.914758838941858, 0.915505962231931,
273
0.916252698812210, 0.916999049082807, 0.917745013443216, 0.918490592292311,
274
0.919235786028347, 0.919980595048962, 0.920725019751180, 0.921469060531410,
275
0.922212717785448, 0.922955991908478, 0.923698883295072, 0.924441392339197,
276
0.925183519434208, 0.925925264972856, 0.926666629347283, 0.927407612949032,
277
0.928148216169037, 0.928888439397636, 0.929628283024562, 0.930367747438952,
278
0.931106833029342, 0.931845540183673, 0.932583869289291, 0.933321820732945,
279
0.934059394900794, 0.934796592178403, 0.935533412950747, 0.936269857602210,
280
0.937005926516589, 0.937741620077096, 0.938476938666352, 0.939211882666397,
281
0.939946452458687, 0.940680648424094, 0.941414470942911, 0.942147920394849,
282
0.942880997159041, 0.943613701614043, 0.944346034137834, 0.945077995107817,
283
0.945809584900821, 0.946540803893103, 0.947271652460349, 0.948002130977671,
284
0.948732239819614, 0.949461979360154, 0.950191349972701, 0.950920352030097,
285
0.951648985904620, 0.952377251967984, 0.953105150591341, 0.953832682145281,
286
0.954559846999833, 0.955286645524468, 0.956013078088099, 0.956739145059080,
287
0.957464846805211, 0.958190183693738, 0.958915156091350, 0.959639764364186,
288
0.960364008877834, 0.961087889997331, 0.961811408087163, 0.962534563511272,
289
0.963257356633048, 0.963979787815339, 0.964701857420447, 0.965423565810129,
290
0.966144913345602, 0.966865900387539, 0.967586527296073, 0.968306794430798,
291
0.969026702150771, 0.969746250814509, 0.970465440779995, 0.971184272404677,
292
0.971902746045467, 0.972620862058745, 0.973338620800360, 0.974056022625630,
293
0.974773067889342, 0.975489756945754, 0.976206090148598, 0.976922067851080,
294
0.977637690405876, 0.978352958165143, 0.979067871480510, 0.979782430703087,
295
0.980496636183459, 0.981210488271695, 0.981923987317340, 0.982637133669424,
296
0.983349927676458, 0.984062369686437, 0.984774460046841, 0.985486199104635,
297
0.986197587206273, 0.986908624697693, 0.987619311924326, 0.988329649231088,
298
0.989039636962390, 0.989749275462133, 0.990458565073711, 0.991167506140010,
299
0.991876099003415, 0.992584344005802, 0.993292241488548, 0.993999791792523,
300
0.994706995258101, 0.995413852225151, 0.996120363033046, 0.996826528020659,
301
0.997532347526366, 0.998237821888046, 0.998942951443085, 0.999647736528371,
305
static double log_table_value(int i) {306
return (log(1.0 + static_cast<double>(i + 0.5) / FastLogCount) / log(2.0));
309
// Ensure initialization checks only happen once during bootstrap
310
static volatile bool log_table_checked = false;
312
// Sanity check all log_table values or print it out if running
313
// -Xlog:heapsampling+generate::none
314
static void verify_or_generate_log_table() {315
log_table_checked = true;
316
assert(is_power_of_2(FastLogCount) && FastLogCount >= 4, "table size should be power of two and at least 4");
317
if (log_is_enabled(Info,heapsampling,generate)) {318
log_info(heapsampling,generate)("FastLogCount = %d", FastLogCount);319
log_info(heapsampling,generate)("static const double log_table[FastLogCount] = {");321
for (; i < FastLogCount; i += 4) {322
double v1 = log_table_value(i);
323
double v2 = log_table_value(i + 1);
324
double v3 = log_table_value(i + 2);
325
double v4 = log_table_value(i + 3);
326
log_info(heapsampling,generate)(" %.15f, %.15f, %.15f, %.15f,", v1, v2, v3, v4);328
log_info(heapsampling,generate)("};");329
assert(i == FastLogCount, "post-loop invariant");
331
// sanity check log_table - disabled when generating
332
for (int i = 0; i < FastLogCount; i++) {333
assert(abs(log_table_value(i) - log_table[i]) < 0.0001,
334
"log_table deviates too much at index: %d %.15f %.15f",
335
i, log_table_value(i), log_table[i]);
341
// Returns the next prng value.
342
// pRNG is: aX+b mod c with a = 0x5DEECE66D, b = 0xB, c = 1<<48
343
// This is the lrand64 generator.
344
uint64_t ThreadHeapSampler::next_random(uint64_t rnd) {345
const uint64_t PrngMult = 0x5DEECE66DLL;
346
const uint64_t PrngAdd = 0xB;
347
const uint64_t PrngModPower = 48;
348
const uint64_t PrngModMask = ((uint64_t)1 << PrngModPower) - 1;
349
//assert(IS_SAFE_SIZE_MUL(PrngMult, rnd), "Overflow on multiplication.");
350
//assert(IS_SAFE_SIZE_ADD(PrngMult * rnd, PrngAdd), "Overflow on addition.");
351
return (PrngMult * rnd + PrngAdd) & PrngModMask;
354
double ThreadHeapSampler::fast_log2(const double& d) {355
assert(d>0, "bad value passed to assert");
357
assert(sizeof(d) == sizeof(x),
358
"double and uint64_t do not have the same size");
359
x = *reinterpret_cast<const uint64_t*>(&d);
360
const uint32_t x_high = checked_cast<uint32_t>(x >> 32);
361
assert(FastLogNumBits <= 20, "FastLogNumBits should be less than 20.");
362
const uint32_t y = x_high >> (20 - FastLogNumBits) & FastLogMask;
363
const int32_t exponent = ((x_high >> 20) & 0x7FF) - 1023;
364
return exponent + log_table[y];
367
// Generates a geometric variable with the specified mean (512K by default).
368
// This is done by generating a random number between 0 and 1 and applying
369
// the inverse cumulative distribution function for an exponential.
370
// Specifically: Let m be the inverse of the sample interval, then
371
// the probability distribution function is m*exp(-mx) so the CDF is
372
// p = 1 - exp(-mx), so
373
// q = 1 - p = exp(-mx)
376
// log_2(q) * (-log_e(2) * 1/m) = x
377
// In the code, q is actually in the range 1 to 2**26, hence the -26 below
378
void ThreadHeapSampler::pick_next_geometric_sample() {379
_rnd = next_random(_rnd);
380
// Take the top 26 bits as the random number
381
// (This plus a 1<<58 sampling bound gives a max possible step of
382
// 5194297183973780480 bytes. In this case,
383
// for sample_parameter = 1<<19, max possible step is
384
// 9448372 bytes (24 bits).
385
const uint64_t PrngModPower = 48; // Number of bits in prng
386
// The uint32_t cast is to prevent a (hard-to-reproduce) NAN
387
// under piii debug for some binaries.
388
double q = static_cast<uint32_t>(_rnd >> (PrngModPower - 26)) + 1.0;
389
// Put the computed p-value through the CDF of a geometric.
390
// For faster performance (save ~1/20th exec time), replace
391
// min(0.0, FastLog2(q) - 26) by (Fastlog2(q) - 26.000705)
392
// The value 26.000705 is used rather than 26 to compensate
393
// for inaccuracies in FastLog2 which otherwise result in a
395
double log_val = (fast_log2(q) - 26);
397
(0.0 < log_val ? 0.0 : log_val) * (-log(2.0) * (get_sampling_interval())) + 1;
398
assert(result > 0 && result < static_cast<double>(SIZE_MAX), "Result is not in an acceptable range.");
399
size_t interval = static_cast<size_t>(result);
400
_bytes_until_sample = interval;
403
void ThreadHeapSampler::pick_next_sample(size_t overflowed_bytes) {405
if (!log_table_checked) {406
verify_or_generate_log_table();
409
// Explicitly test if the sampling interval is 0, return 0 to sample every
411
if (get_sampling_interval() == 0) {412
_bytes_until_sample = 0;
416
pick_next_geometric_sample();
419
void ThreadHeapSampler::check_for_sampling(oop obj, size_t allocation_size, size_t bytes_since_allocation) {420
size_t total_allocated_bytes = bytes_since_allocation + allocation_size;
422
// If not yet time for a sample, skip it.
423
if (total_allocated_bytes < _bytes_until_sample) {424
_bytes_until_sample -= total_allocated_bytes;
428
JvmtiExport::sampled_object_alloc_event_collector(obj);
430
size_t overflow_bytes = total_allocated_bytes - _bytes_until_sample;
431
pick_next_sample(overflow_bytes);
434
int ThreadHeapSampler::get_sampling_interval() {435
return Atomic::load_acquire(&_sampling_interval);
438
void ThreadHeapSampler::set_sampling_interval(int sampling_interval) {439
Atomic::release_store(&_sampling_interval, sampling_interval);