javaGC筆記-創(chuàng)新互聯(lián)

以hbase為例：在hbase的配置文件路徑下，設置了GC log輸出路徑/app/hbase-config/hbase-env.sh

10余年的登封網(wǎng)站建設經(jīng)驗，針對設計、前端、開發(fā)、售后、文案、推廣等六對一服務，響應快，48小時及時工作處理。全網(wǎng)整合營銷推廣的優(yōu)勢是能夠根據(jù)用戶設備顯示端的尺寸不同，自動調(diào)整登封建站的顯示方式，使網(wǎng)站能夠適用不同顯示終端，在瀏覽器中調(diào)整網(wǎng)站的寬度，無論在任何一種瀏覽器上瀏覽網(wǎng)站，都能展現(xiàn)優(yōu)雅布局與設計，從而大程度地提升瀏覽體驗。成都創(chuàng)新互聯(lián)公司從事“登封網(wǎng)站設計”,“登封網(wǎng)站推廣”以來，每個客戶項目都認真落實執(zhí)行。

export HBASE_OPTS="-Xmx16384m -Xms16384m -Xmn8192m -XX:PermSize=160M -XX:MaxPermSize=160M -XX:+UseConcMarkSweepGC -XX:+UseParNewGC  -XX:CMSInitiatingOccupancyFraction=70 -XX:+UseCMSCompactAtFullCollection -XX:CMSFullGCsBeforeCompaction=3  -XX:+CMSParallelRemarkEnabled -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCApplicationStoppedTime -XX:PrintFLSStatistics=1 -Xloggc:/app/hbase/logs/hbase_gc.log $HBASE_OPTS"

可以查詢到log的相關信息

#jstat -gccause 79751 1000 1000 //獲取GC相關指標，表示每1000毫秒查詢一次79751垃圾收集狀況。
Usage: jstat -help|-options
?????? jstat -<option> [-t] [-h<lines>] <vmid> [<interval> [<count>]]
?參數(shù)解釋：
Options — 選項，我們一般使用 -gcutil 查看gc情況
vmid??? — VM的進程號，即當前運行的java進程號
interval– 間隔時間，單位為秒或者毫秒
count?? — 打印次數(shù)，如果缺省則打印無數(shù)次

S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT    LGCC                 GCC
  0.00   8.98  11.16  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  12.79  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  14.94  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  16.04  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  17.98  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  20.34  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  21.83  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC
  0.00   8.98  22.64  69.83  12.33    156   50.788    16  280.103  330.891 unknown GCCause      No GC

E列代表
O E-->O 新生代轉(zhuǎn)移到老代，Ｏ積累到80%就會觸發(fā)full gc

具體意思如下：
E（表示，Eden），代表這臺服務器的新生代Eden區(qū)使用了11.16的空間，
S0 S1 兩個Survivor區(qū)(S0,S1表示Survivor0、Survivor1),Survivor0里面是空的，Survivor1占了8.98%

老年代（O，表示old) 和永久帶（P，表示Permanent）分別使用了69.83% 和12.33%的空間。
程序運行以來共發(fā)生Minor GC(YGC ,表示young gc)156次，總耗時50.788秒；
發(fā)生Fulle GC （FGC，表示full GC ）16次，full GC總耗時（FGCT，表示full gc time）為330.891秒，總的GC總耗時（GCT，表示GC Time）為330.891秒
LGCC Cause of last Garbage Collection.
GCC Cause of current Garbage Collection.

Java 6 JDK輸出如下：
[hadoop@0321 logs]$ jmap -heap 29877

Attaching to process ID 29877, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.45-b01

using parallel threads in the new generation.
using thread-local object allocation.
Concurrent Mark-Sweep GC

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize      = 21474836480 (20480.0MB)
   NewSize          = 4294967296 (4096.0MB)
   MaxNewSize       = 4294967296 (4096.0MB)
   OldSize          = 5439488 (5.1875MB)
   NewRatio         = 2
   SurvivorRatio    = 8
   PermSize         = 67108864 (64.0MB)
   MaxPermSize      = 67108864 (64.0MB)

Heap Usage:
New Generation (Eden + 1 Survivor Space):
   capacity = 3865509888 (3686.4375MB)
   used     = 481048576 (458.763671875MB)
   free     = 3384461312 (3227.673828125MB)
   12.444634470949257% used
Eden Space:
   capacity = 3436052480 (3276.875MB)
   used     = 481048576 (458.763671875MB)
   free     = 2955003904 (2818.111328125MB)
   14.00003576196834% used
From Space:
   capacity = 429457408 (409.5625MB)
   used     = 0 (0.0MB)
   free     = 429457408 (409.5625MB)
   0.0% used
To Space:
   capacity = 429457408 (409.5625MB)
   used     = 0 (0.0MB)
   free     = 429457408 (409.5625MB)
   0.0% used
concurrent mark-sweep generation:
   capacity = 12884901888 (12288.0MB)
   used     = 0 (0.0MB)
   free     = 12884901888 (12288.0MB)
   0.0% used
Perm Generation:
   capacity = 67108864 (64.0MB)
   used     = 21153816 (20.173851013183594MB)
   free     = 45955048 (43.826148986816406MB)
   31.521642208099365% used

Eden from to 3個加起來為Young 區(qū)

[hbase@0321 ~]$ jps
10424 Jps
8229 HRegionServer

[hbase@0321 ~]$ jmap -heap 8229
Attaching to process ID 8229, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 24.71-b01

using thread-local object allocation.
Garbage-First (G1) GC with 6 thread(s)

Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 25769803776 (24576.0MB)
NewSize = 1363144 (1.2999954223632812MB)
MaxNewSize = 17592186044415 MB
OldSize = 5452592 (5.1999969482421875MB)
NewRatio = 2
SurvivorRatio = 8
PermSize = 16777216 (16.0MB)
MaxPermSize = 83886080 (80.0MB)
G1HeapRegionSize = 8388608 (8.0MB)

Heap Usage:
G1 Heap:
regions = 3072
capacity = 25769803776 (24576.0MB)
used = 20409483264 (19464.0MB)
free = 5360320512 (5112.0MB)
79.19921875% used
G1 Young Generation:
Eden Space:
regions = 89
capacity = 1182793728 (1128.0MB)
used = 746586112 (712.0MB)
free = 436207616 (416.0MB)
63.12056737588652% used
Survivor Space:
regions = 20
capacity = 167772160 (160.0MB)
used = 167772160 (160.0MB)
free = 0 (0.0MB)
100.0% used
G1 Old Generation:
regions = 2324
capacity = 24419237888 (23288.0MB)
used = 19495124992 (18592.0MB)
free = 4924112896 (4696.0MB)
79.83510821023704% used
Perm Generation:
capacity = 50331648 (48.0MB)
used = 42303832 (40.344078063964844MB)
free = 8027816 (7.655921936035156MB)
84.05016263326009% used

G1 GC筆記：

關于大gc停頓時間
在做minor gc和mixed gc時，收集器會在內(nèi)存中維系一個remembered set，這個set包含了heap中所有對象的引用，用以確定哪些可以被回收。
每次gc時，g1會通過一個預測模型來計算每個region進行回收的時間，從而從中選出停頓時間在MaxGCPauseMillis之內(nèi)的region進行垃圾回收
?

關于mixed gc

mixed gc是一種既回收young區(qū)，也回收old區(qū)的垃圾回收方式，它觸發(fā)的條件是-XX:InitiatingHeapOccupancyPercent，mixed gc的目的就是為了延遲full gc的產(chǎn)生

同理YGC指的是回收young的垃圾回收方式

Full GC 指的是回收Old去的垃圾回收方式，因為old區(qū)比較大，導致GC時間比較長，并且在GC期間java進程停止對外相應，并且自身也不對外響應，導致regionserver無法向zookeeper注冊心跳信息，超過zookeeper （ <name>zookeeper.session.timeout</name>） session時間，就會被zookeeper置為dead。

Hbase G1參數(shù)調(diào)整：

待修改的參數(shù)，修改GC的參數(shù)需要重啟集群，安排在下次重啟。

-XX:ConcGCThreads=12并發(fā)標記的執(zhí)行線程數(shù) =================== 測試數(shù)據(jù)ConcGCThreads 不能大于-XX:ParallelGCThreads，否則會報錯
-XX:InitiatingHeapOccupancyPercent=60? 堆占用了多少的時候就觸發(fā)GC，默認為45
-XX:ParallelGCThreads=12 30

[hbase@0321 ~]$ jstat -gccapacity 61540
NGCMN NGCMX NGC S0C S1C EC OGCMN OGCMX OGC OC PGCMN PGCMX PGC PC YGC FGC
0.0 52428800.0 2490368.0 0.0 294912.0 2195456.0 0.0 52428800.0 44695552.0 44695552.0 16384.0 81920.0 49152.0 49152.0 2 0

GC 常見命令：

[hbase@ 0321 ~]$ jmap -heap 61540

Attaching to process ID 61540, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 24.71-b01

using thread-local object allocation.
Garbage-First (G1) GC with 30 thread(s)

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize      = 53687091200 (51200.0MB)
   NewSize          = 1363144 (1.2999954223632812MB)
   MaxNewSize       = 17592186044415 MB
   OldSize          = 5452592 (5.1999969482421875MB)
   NewRatio         = 2
   SurvivorRatio    = 8
   PermSize         = 16777216 (16.0MB)
   MaxPermSize      = 83886080 (80.0MB)
   G1HeapRegionSize = 16777216 (16.0MB)

Heap Usage:
G1 Heap:
   regions  = 2880
   capacity = 48318382080 (46080.0MB)
   used     = 2519304864 (2402.5963439941406MB)
   free     = 45799077216 (43677.40365600586MB)
   5.213967760403951% used
G1 Young Generation:
Eden Space:
   regions  = 7
   capacity = 2248146944 (2144.0MB)
   used     = 117440512 (112.0MB)
   free     = 2130706432 (2032.0MB)
   5.223880597014926% used
Survivor Space:
   regions  = 18
   capacity = 301989888 (288.0MB)
   used     = 301989888 (288.0MB)
   free     = 0 (0.0MB)
   100.0% used
G1 Old Generation:
   regions  = 126
   capacity = 45768245248 (43648.0MB)
   used     = 2099874464 (2002.5963439941406MB)
   free     = 43668370784 (41645.40365600586MB)
   4.588059805705051% used
Perm Generation:
   capacity = 50331648 (48.0MB)
   used     = 42610464 (40.636505126953125MB)
   free     = 7721184 (7.363494873046875MB)
   84.65938568115234% used

13018 interned Strings occupying 1388240 bytes.

[hbase@0321 ~]$ jstat -gccause -h 10 61540 1000 1000

  S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT    LGCC                 GCC
  0.00 100.00  92.54  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00  92.54  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00  92.54  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00  93.28  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00  93.28  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00  93.28  20.26  85.06     16    1.794     0    0.000    1.794 G1 Evacuation Pause  No GC
  0.00 100.00   1.42  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   1.42  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT    LGCC                 GCC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   3.55  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT    LGCC                 GCC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC
  0.00 100.00   4.26  21.24  85.06     17    1.877     0    0.000    1.877 G1 Evacuation Pause  No GC

#jstat -gcutil 27912 1s 50

另外有需要云服務器可以了解下創(chuàng)新互聯(lián)scvps.cn，海內(nèi)外云服務器15元起步，三天無理由+7*72小時售后在線，公司持有idc許可證，提供“云服務器、裸金屬服務器、高防服務器、香港服務器、美國服務器、虛擬主機、免備案服務器”等云主機租用服務以及企業(yè)上云的綜合解決方案，具有“安全穩(wěn)定、簡單易用、服務可用性高、性價比高”等特點與優(yōu)勢，專為企業(yè)上云打造定制，能夠滿足用戶豐富、多元化的應用場景需求。

名稱欄目：javaGC筆記-創(chuàng)新互聯(lián)
URL鏈接：http://muchs.cn/article2/dsghic.html

成都網(wǎng)站建設公司_創(chuàng)新互聯(lián)，為您提供網(wǎng)站制作、虛擬主機、網(wǎng)站建設、Google、電子商務、網(wǎng)站收錄

聲明：本網(wǎng)站發(fā)布的內(nèi)容（圖片、視頻和文字）以用戶投稿、用戶轉(zhuǎn)載內(nèi)容為主，如果涉及侵權請盡快告知，我們將會在第一時間刪除。文章觀點不代表本網(wǎng)站立場，如需處理請聯(lián)系客服。電話：028-86922220；郵箱：631063699@qq.com。內(nèi)容未經(jīng)允許不得轉(zhuǎn)載，或轉(zhuǎn)載時需注明來源：創(chuàng)新互聯(lián)

猜你還喜歡下面的內(nèi)容