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I'm trying to use an EC2 'micro' AMI (their recommended micro 32-bit AMI, ami-7f418316, which has kernel to run a grails app (grails 2.0.0 BUILD-SNAPSHOT from github grails-core, so this is post-M2). It sometimes works, then sometimes when grails is starting up (before I do run-app) it will go into a 100% java or java + rsyslogd lockup, dumping a bunch of /var/log/message that look like there's something going on with memory mapping:

[180297.535565] ------------[ cut here ]------------
[180297.535572] WARNING: at arch/x86/xen/multicalls.c:182 xen_mc_flush+0x224/0x250()
[180297.535580] Modules linked in: ipv6 binfmt_misc dm_mirror dm_region_hash dm_log
dm_mod rtc_core rtc_lib ext4 mbcache jbd2 crc16 uhci_hcd ohci_hcd ssb ehci_hcd usbcore
nls_base [last unloaded: scsi_wait_scan]
[180297.535638] Pid: 24986, comm: java Tainted: G      D W #1
[180297.535646] Call Trace:
[180297.535653]  [<c104282d>] warn_slowpath_common+0x6d/0xa0
[180297.535661]  [<c1004a44>] ? xen_mc_flush+0x224/0x250
[180297.535669]  [<c1004a44>] ? xen_mc_flush+0x224/0x250
[180297.535678]  [<c104287d>] warn_slowpath_null+0x1d/0x20
[180297.535686]  [<c1004a44>] xen_mc_flush+0x224/0x250
[180297.535694]  [<c10063ae>] ? xen_extend_mmu_update+0xce/0x190
[180297.535703]  [<c100650d>] xen_set_pud_hyper+0x9d/0xc0
[180297.535711]  [<c10065a4>] xen_set_pud+0x74/0xc0
[180297.535719]  [<c102cf90>] pud_populate+0x40/0x80
[180297.535726]  [<c10b1b73>] __pmd_alloc+0x73/0x80
[180297.535735]  [<c12aefd0>] ? do_page_fault+0x0/0x400
[180297.535743]  [<c10b63e2>] handle_mm_fault+0xd22/0xdc0
[180297.535751]  [<c1004922>] ? xen_mc_flush+0x102/0x250
[180297.535759]  [<c1005b06>] ? arbitrary_virt_to_machine+0x86/0xc0
[180297.535768]  [<c12aefd0>] ? do_page_fault+0x0/0x400
[180297.535776]  [<c12af0fc>] do_page_fault+0x12c/0x400
[180297.535784]  [<c1036df1>] ? finish_task_switch+0x41/0x90
[180297.535793]  [<c1048015>] ? irq_exit+0x35/0x70
[180297.535801]  [<c12aefd0>] ? do_page_fault+0x0/0x400
[180297.535809]  [<c12ac637>] error_code+0x73/0x78
[180297.535817]  [<c12a0000>] ? quirk_usb_early_handoff+0xd6/0x579
[180297.535824] ---[ end trace a7919e7f17c0c5a0 ]---

I've tried with both the openjdk and the sun jdk, same (intermittent) symptom. Any idea whether this is a clue that grails 2 is just not going to work on Amazon EC2, or is likely to be worth trying on a bigger instance? Or should I just shift over to cloudfoundry for grails apps these days?

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up vote 1 down vote accepted

I tried 32 and 64 bit micro versions of the Amazon Linux AMI: same (flaky) result. The 64-bit got killed faster (I think that's because there's no swap device on that AMI). So then I switched from the micro to a small 32-bit version and it's running fine. I didn't try any non-default memory tuning of grails, this will do for now.

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Please mark this as your accepted answer :) – pauska Oct 7 '11 at 12:34
OK (I wasn't sure about the ethos there). – Wayne Oct 7 '11 at 21:22

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