Java 命令行 -XshowSettings 查看 JVM 配置

showSettings

显示JVM的配置。

-XshowSettings:category

显示不同category的配置。

category=vm

显示最大堆的可能大小。

java -XshowSettings:vm -version

输出

bash-4.4$ java -XshowSettings:vm -version
VM settings:
    Max. Heap Size (Estimated): 3.10G
    Using VM: OpenJDK 64-Bit Server VM

openjdk version "11.0.16" 2022-07-19
OpenJDK Runtime Environment 18.9 (build 11.0.16+8)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.16+8, mixed mode, sharing)

category=system

只有Linux系统会有此选项，查看系统或容器的配置。

java -XshowSettings:system -version

输出

bash-4.4$ java -XshowSettings:system -version
Operating System Metrics:
    Provider: cgroupv1
    Effective CPU Count: 1
    CPU Period: 100000us
    CPU Quota: -1
    CPU Shares: 2us
    List of Processors, 4 total: 
    0 1 2 3 
    List of Effective Processors, 4 total: 
    0 1 2 3 
    List of Memory Nodes, 1 total: 
    0 
    List of Available Memory Nodes, 1 total: 
    0 
    Memory Limit: 12.84G
    Memory Soft Limit: Unlimited
    Memory & Swap Limit: Unlimited

openjdk version "11.0.16" 2022-07-19
OpenJDK Runtime Environment 18.9 (build 11.0.16+8)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.16+8, mixed mode, sharing)

category=properties

显示系统变量的配置。

java -XshowSettings:properties -version

category=locale

显示locale本地化配置。

java -XshowSettings:locale -version

-XshowSettings

显示所有的配置。

java -XshowSettings -version

等同于

java -XshowSettings:all -version

输出

bash-4.4# java -XshowSettings -version
VM settings:
    Max. Heap Size (Estimated): 3.10G
    Using VM: OpenJDK 64-Bit Server VM

Property settings:
    awt.toolkit = sun.awt.X11.XToolkit
    file.encoding = UTF-8
    file.separator = /
    java.awt.graphicsenv = sun.awt.X11GraphicsEnvironment
    java.awt.printerjob = sun.print.PSPrinterJob
    java.class.path = 
    java.class.version = 55.0
    java.home = /usr/java/openjdk-11
    java.io.tmpdir = /tmp
    java.library.path = /usr/java/packages/lib
        /usr/lib64
        /lib64
        /lib
        /usr/lib
    java.runtime.name = OpenJDK Runtime Environment
    java.runtime.version = 11.0.16+8
    java.specification.name = Java Platform API Specification
    java.specification.vendor = Oracle Corporation
    java.specification.version = 11
    java.vendor = Oracle Corporation
    java.vendor.url = https://openjdk.java.net/
    java.vendor.url.bug = https://bugreport.java.com/bugreport/
    java.vendor.version = 18.9
    java.version = 11.0.16
    java.version.date = 2022-07-19
    java.vm.compressedOopsMode = Zero based
    java.vm.info = mixed mode, sharing
    java.vm.name = OpenJDK 64-Bit Server VM
    java.vm.specification.name = Java Virtual Machine Specification
    java.vm.specification.vendor = Oracle Corporation
    java.vm.specification.version = 11
    java.vm.vendor = Oracle Corporation
    java.vm.version = 11.0.16+8
    jdk.debug = release
    line.separator = \n 
    os.arch = amd64
    os.name = Linux
    os.version = 4.19.91-24.1.al7.x86_64
    path.separator = :
    sun.arch.data.model = 64
    sun.boot.library.path = /usr/java/openjdk-11/lib
    sun.cpu.endian = little
    sun.cpu.isalist = 
    sun.io.unicode.encoding = UnicodeLittle
    sun.java.launcher = SUN_STANDARD
    sun.jnu.encoding = UTF-8
    sun.management.compiler = HotSpot 64-Bit Tiered Compilers
    sun.os.patch.level = unknown
    user.dir = /dir
    user.home = /root
    user.language = en
    user.name = root
    user.timezone = 

Locale settings:
    default locale = English
    default display locale = English
    default format locale = English
    available locales = , af, af_NA, af_ZA, agq, agq_CM, ak, ak_GH, 
        am, am_ET, ar, ar_001, ar_AE, ar_BH, ar_DJ, ar_DZ, 
        ar_EG, ar_EH, ar_ER, ar_IL, ar_IQ, ar_JO, ar_KM, ar_KW, 
        ar_LB, ar_LY, ar_MA, ar_MR, ar_OM, ar_PS, ar_QA, ar_SA, 
        ar_SD, ar_SO, ar_SS, ar_SY, ar_TD, ar_TN, ar_YE, as, 
        as_IN, asa, asa_TZ, ast, ast_ES, az, az_AZ_#Cyrl, az_AZ_#Latn, 
        az__#Cyrl, az__#Latn, bas, bas_CM, be, be_BY, bem, bem_ZM, 
        bez, bez_TZ, bg, bg_BG, bm, bm_ML, bn, bn_BD, 
        bn_IN, bo, bo_CN, bo_IN, br, br_FR, brx, brx_IN, 
        bs, bs_BA_#Cyrl, bs_BA_#Latn, bs__#Cyrl, bs__#Latn, ca, ca_AD, ca_ES, 
        ca_ES_VALENCIA, ca_FR, ca_IT, ccp, ccp_BD, ccp_IN, ce, ce_RU, 
        cgg, cgg_UG, chr, chr_US, ckb, ckb_IQ, ckb_IR, cs, 
        cs_CZ, cu, cu_RU, cy, cy_GB, da, da_DK, da_GL, 
        dav, dav_KE, de, de_AT, de_BE, de_CH, de_DE, de_IT, 
        de_LI, de_LU, dje, dje_NE, dsb, dsb_DE, dua, dua_CM, 
        dyo, dyo_SN, dz, dz_BT, ebu, ebu_KE, ee, ee_GH, 
        ee_TG, el, el_CY, el_GR, en, en_001, en_150, en_AG, 
        en_AI, en_AS, en_AT, en_AU, en_BB, en_BE, en_BI, en_BM, 
        en_BS, en_BW, en_BZ, en_CA, en_CC, en_CH, en_CK, en_CM, 
        en_CX, en_CY, en_DE, en_DG, en_DK, en_DM, en_ER, en_FI, 
        en_FJ, en_FK, en_FM, en_GB, en_GD, en_GG, en_GH, en_GI, 
        en_GM, en_GU, en_GY, en_HK, en_IE, en_IL, en_IM, en_IN, 
        en_IO, en_JE, en_JM, en_KE, en_KI, en_KN, en_KY, en_LC, 
        en_LR, en_LS, en_MG, en_MH, en_MO, en_MP, en_MS, en_MT, 
        en_MU, en_MW, en_MY, en_NA, en_NF, en_NG, en_NL, en_NR, 
        en_NU, en_NZ, en_PG, en_PH, en_PK, en_PN, en_PR, en_PW, 
        en_RW, en_SB, en_SC, en_SD, en_SE, en_SG, en_SH, en_SI, 
        en_SL, en_SS, en_SX, en_SZ, en_TC, en_TK, en_TO, en_TT, 
        en_TV, en_TZ, en_UG, en_UM, en_US, en_US_POSIX, en_VC, en_VG, 
        en_VI, en_VU, en_WS, en_ZA, en_ZM, en_ZW, eo, eo_001, 
        es, es_419, es_AR, es_BO, es_BR, es_BZ, es_CL, es_CO, 
        es_CR, es_CU, es_DO, es_EA, es_EC, es_ES, es_GQ, es_GT, 
        es_HN, es_IC, es_MX, es_NI, es_PA, es_PE, es_PH, es_PR, 
        es_PY, es_SV, es_US, es_UY, es_VE, et, et_EE, eu, 
        eu_ES, ewo, ewo_CM, fa, fa_AF, fa_IR, ff, ff_CM, 
        ff_GN, ff_MR, ff_SN, fi, fi_FI, fil, fil_PH, fo, 
        fo_DK, fo_FO, fr, fr_BE, fr_BF, fr_BI, fr_BJ, fr_BL, 
        fr_CA, fr_CD, fr_CF, fr_CG, fr_CH, fr_CI, fr_CM, fr_DJ, 
        fr_DZ, fr_FR, fr_GA, fr_GF, fr_GN, fr_GP, fr_GQ, fr_HT, 
        fr_KM, fr_LU, fr_MA, fr_MC, fr_MF, fr_MG, fr_ML, fr_MQ, 
        fr_MR, fr_MU, fr_NC, fr_NE, fr_PF, fr_PM, fr_RE, fr_RW, 
        fr_SC, fr_SN, fr_SY, fr_TD, fr_TG, fr_TN, fr_VU, fr_WF, 
        fr_YT, fur, fur_IT, fy, fy_NL, ga, ga_IE, gd, 
        gd_GB, gl, gl_ES, gsw, gsw_CH, gsw_FR, gsw_LI, gu, 
        gu_IN, guz, guz_KE, gv, gv_IM, ha, ha_GH, ha_NE, 
        ha_NG, haw, haw_US, hi, hi_IN, hr, hr_BA, hr_HR, 
        hsb, hsb_DE, hu, hu_HU, hy, hy_AM, ig, ig_NG, 
        ii, ii_CN, in, in_ID, is, is_IS, it, it_CH, 
        it_IT, it_SM, it_VA, iw, iw_IL, ja, ja_JP, ja_JP_JP_#u-ca-japanese, 
        jgo, jgo_CM, ji, ji_001, jmc, jmc_TZ, ka, ka_GE, 
        kab, kab_DZ, kam, kam_KE, kde, kde_TZ, kea, kea_CV, 
        khq, khq_ML, ki, ki_KE, kk, kk_KZ, kkj, kkj_CM, 
        kl, kl_GL, kln, kln_KE, km, km_KH, kn, kn_IN, 
        ko, ko_KP, ko_KR, kok, kok_IN, ks, ks_IN, ksb, 
        ksb_TZ, ksf, ksf_CM, ksh, ksh_DE, kw, kw_GB, ky, 
        ky_KG, lag, lag_TZ, lb, lb_LU, lg, lg_UG, lkt, 
        lkt_US, ln, ln_AO, ln_CD, ln_CF, ln_CG, lo, lo_LA, 
        lrc, lrc_IQ, lrc_IR, lt, lt_LT, lu, lu_CD, luo, 
        luo_KE, luy, luy_KE, lv, lv_LV, mas, mas_KE, mas_TZ, 
        mer, mer_KE, mfe, mfe_MU, mg, mg_MG, mgh, mgh_MZ, 
        mgo, mgo_CM, mk, mk_MK, ml, ml_IN, mn, mn_MN, 
        mr, mr_IN, ms, ms_BN, ms_MY, ms_SG, mt, mt_MT, 
        mua, mua_CM, my, my_MM, mzn, mzn_IR, naq, naq_NA, 
        nb, nb_NO, nb_SJ, nd, nd_ZW, nds, nds_DE, nds_NL, 
        ne, ne_IN, ne_NP, nl, nl_AW, nl_BE, nl_BQ, nl_CW, 
        nl_NL, nl_SR, nl_SX, nmg, nmg_CM, nn, nn_NO, nnh, 
        nnh_CM, no, no_NO, no_NO_NY, nus, nus_SS, nyn, nyn_UG, 
        om, om_ET, om_KE, or, or_IN, os, os_GE, os_RU, 
        pa, pa_IN_#Guru, pa_PK_#Arab, pa__#Arab, pa__#Guru, pl, pl_PL, prg, 
        prg_001, ps, ps_AF, pt, pt_AO, pt_BR, pt_CH, pt_CV, 
        pt_GQ, pt_GW, pt_LU, pt_MO, pt_MZ, pt_PT, pt_ST, pt_TL, 
        qu, qu_BO, qu_EC, qu_PE, rm, rm_CH, rn, rn_BI, 
        ro, ro_MD, ro_RO, rof, rof_TZ, ru, ru_BY, ru_KG, 
        ru_KZ, ru_MD, ru_RU, ru_UA, rw, rw_RW, rwk, rwk_TZ, 
        sah, sah_RU, saq, saq_KE, sbp, sbp_TZ, sd, sd_PK, 
        se, se_FI, se_NO, se_SE, seh, seh_MZ, ses, ses_ML, 
        sg, sg_CF, shi, shi_MA_#Latn, shi_MA_#Tfng, shi__#Latn, shi__#Tfng, si, 
        si_LK, sk, sk_SK, sl, sl_SI, smn, smn_FI, sn, 
        sn_ZW, so, so_DJ, so_ET, so_KE, so_SO, sq, sq_AL, 
        sq_MK, sq_XK, sr, sr_BA, sr_BA_#Cyrl, sr_BA_#Latn, sr_CS, sr_ME, 
        sr_ME_#Cyrl, sr_ME_#Latn, sr_RS, sr_RS_#Cyrl, sr_RS_#Latn, sr_XK_#Cyrl, sr_XK_#Latn, sr__#Cyrl, 
        sr__#Latn, sv, sv_AX, sv_FI, sv_SE, sw, sw_CD, sw_KE, 
        sw_TZ, sw_UG, ta, ta_IN, ta_LK, ta_MY, ta_SG, te, 
        te_IN, teo, teo_KE, teo_UG, tg, tg_TJ, th, th_TH, 
        th_TH_TH_#u-nu-thai, ti, ti_ER, ti_ET, tk, tk_TM, to, to_TO, 
        tr, tr_CY, tr_TR, tt, tt_RU, twq, twq_NE, tzm, 
        tzm_MA, ug, ug_CN, uk, uk_UA, ur, ur_IN, ur_PK, 
        uz, uz_AF_#Arab, uz_UZ_#Cyrl, uz_UZ_#Latn, uz__#Arab, uz__#Cyrl, uz__#Latn, vai, 
        vai_LR_#Latn, vai_LR_#Vaii, vai__#Latn, vai__#Vaii, vi, vi_VN, vo, vo_001, 
        vun, vun_TZ, wae, wae_CH, wo, wo_SN, xog, xog_UG, 
        yav, yav_CM, yo, yo_BJ, yo_NG, yue, yue_CN_#Hans, yue_HK_#Hant, 
        yue__#Hans, yue__#Hant, zgh, zgh_MA, zh, zh_CN, zh_CN_#Hans, zh_HK, 
        zh_HK_#Hans, zh_HK_#Hant, zh_MO_#Hans, zh_MO_#Hant, zh_SG, zh_SG_#Hans, zh_TW, zh_TW_#Hant, 
        zh__#Hans, zh__#Hant, zu, zu_ZA
Operating System Metrics:
    Provider: cgroupv1
    Effective CPU Count: 1
    CPU Period: 100000us
    CPU Quota: -1
    CPU Shares: 2us
    List of Processors, 4 total: 
    0 1 2 3 
    List of Effective Processors, 4 total: 
    0 1 2 3 
    List of Memory Nodes, 1 total: 
    0 
    List of Available Memory Nodes, 1 total: 
    0 
    Memory Limit: 12.84G
    Memory Soft Limit: Unlimited
    Memory & Swap Limit: Unlimited

openjdk version "11.0.16" 2022-07-19
OpenJDK Runtime Environment 18.9 (build 11.0.16+8)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.16+8, mixed mode, sharing)

参考

Java 11

https://docs.oracle.com/en/java/javase/11/tools/java.html

Java 8

https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html